Gemstone Glossary

Gemstone Guide – Gemstone Glossary

Knowledge of gemstones will bring you to further questions and make you inquisitive about the various terminologies associated with gemstones and its jewelry. To quench this thirst of knowing more, you can visit our Gemstone Glossary.

Term Description
Alexandrite Alexandrite is a form of the mineral Chrysoberyl which is a very attractive and rare stone. It is 8.5 on Mohs hardness scale and mainly found in Russia, Sri Lanka, Brazil, Burma, Madagascar and USA. The most sensational feature about this stone is its surprising ability to change its color under different forms of light. Green or bluish-green in daylight, red in candle light, green in fluorescent light and reddish-purple in standard electric (tungsten) light.
Alluvial Stones those have been sourced from alluvial deposits in river beds or transported by water and deposited in seas and lakes. Many gems, including diamonds, are found in alluvial deposits and Alluvial stones are usually of gem quality.
Amber The gemstone Amber is the fossilized liquid, resin, or gum from pine trees and available in various colors like golden yellow, golden orange, brown, green, red and violet. These gemstones may contain insects, plant material, feathers and other small objects that were trapped millions of years ago when the resin was sticky. Amber is quite soft but perfect for jewelry as it can be easily cut, etched, faceted, or carved.
American Cut Marcel Tolkowsky’s mathematically calculated ideal proportions and facet angles, to produce maximum brilliancy consistent with a high degree of fire in a round brilliant gemstone. This is known as American Cut or Ideal Cut.
Amethyst Amethyst is a variety from Quartz family, colored by traces of manganese, titanium and iron. Deeper-colored amethysts are more highly valued. It is available in colors like purple, pale lavender to deep reddish purple, bluish violet etc. Rich purple has always been a rare and noble color. Amethyst’s name comes from Greek word ‘Amethystos’ meaning ‘Not Intoxicated’ or ‘Not Drunken’. The Amethyst is said to bring good luck and to radiate love. This brilliantly sparkling stone is the most valued gemstone from the quartz family. It is 7 on Mohs hardness scale and mainly found in Sri Lanka, Brazil, Burma, Canada, East Africa, India, North America, Russia, Uruguay, Madagascar and Australia.
Appraisal Appraisal is a written statement based on estimated retail replacement value of the gemstone or piece of jewelry. Appraisal is mainly used for insurance purposes and should be updated after every few years.
Aquamarine Aquamarine is a variety of mineral Beryl. This is a fascinatingly beautiful gemstone found in colors like light blue of the sky to the deep blue of the sea. The more intense the color of an Aquamarine, the more value is put on it. Its hardness makes it very tough which comes in between 7.5 to 8 on Mohs hardness scale and it is mainly found in Brazil, Madagascar, Russia, Afghanistan, India, Pakistan, Nigeria, Zambia, Mozambique and USA. Its name is derived from the Latin ‘Aqua’ (water) and ‘Mare’ (sea). Aquamarine is one of the most popular and best-known gemstones.
Asterism Asterism is the star effect that appears on some gemstones. This star effect is a reflection that appears as two or more intersecting bands of light across the surface of a gem. Usually asterism is found in Ruby, Sapphire and Garnet.
Aventurescent Aventurescent gemstones are those which display a colorful play of sparkling reflections due to small metallic inclusions.
Baguette Baguette is a French word meaning ‘Rod’. It is a step cut for small rectangular shaped gemstones and diamonds.
Bar Setting In this style of setting, gemstones are individually set between these bars leaving the sides of the stones exposed to light. This method maximizes the amount of light entering the gemstones which create superior brilliance and sparkle.
Baroque Baroque is a term that refers to irregularly or oddly shaped stones mainly pearls. Baroque pearls can be natural or artificial.
Beryl The name beryl comes from ancient Greek word ‘beryllos’ which means precious blue-green color. This stone is available in a variety of colors including green, yellow, greenish-yellow, blue to blue-green, red, colorless and pink.
Bezel Setting In this style of setting, a metal rim gently holds a gemstone in place by the girdle. The bezel setting guards the gemstone from any damages and yet allows light to enter which creates brilliance and sparkle.
Birthstone A birthstone is nothing but a stone, which is associated with the date of one’s birth and wearing of such birthstone is considered to bring good luck and health. Certain stones are believed to have Supernatural powers and their relationship with planets. Many cultures originally assigned a specific stone to signify birth during each sign of the zodiac but over the time this tradition has been shifted from the zodiac to calendar months. Following birthstones are assigned for every calendar month. January – Garnet, February – Amethyst, March – Aquamarine, April – Diamond, May – Emerald, June – Pearl / Alexandrite / Moonstone, July – Ruby, August – Peridot / Sardonyx, September – Sapphire, October – Opal / Pink Tourmaline, November – Citrine / Yellow Topaz, December – Turquoise / Tanzanite / Zircon / Blue Topaz.
Blemish An external mark or surface imperfection on a gemstone. For example, a nick, abrasion, knot, scratch, minor crack or fissure (cavity), or a poor polish. A natural or an extra facet is also considered a blemish.
Brilliance Brilliance describes the reflections of white light returned to the eye from a gemstone. Brilliance is produced primarily when light enters through the table, reaches the pavilion facets, and is then reflected back out through the table. The major factors that affect the amount of brilliancy in a gem are refractive index, proportions, polish and transparency.
Brilliant Cut Brilliant Cut is the most common style of gemstone cutting and it is called a brilliant cut because it is designed to maximize brilliance. The standard round brilliant cut consists of a total of 58 facets which covers 1 table, 8 bezel facets, 8 star facets and 16 upper-girdle facets on the crown; and 8 pavilion facets, 16 lower-girdle facets, and usually a culet on the pavilion, or base. Brilliant cut stones normally come in round shape, but there are modified variants in other shapes also.
Briolette This term is used for a long teardrop shaped gemstone with rose cut facets, which sometimes is also drilled to be used as a pendant.

 

Cabochon Cut A cabochon shaped gemstone resembles a dome as it comes in round shape with no facets. Generally onyx stone is cut in a cabochon shape.
Cameo Cameo is a style of carving in which the design pattern is left and the surrounding surface is cut away leaving the design in relief. This is done to use the natural colors of the stone or shell to produce the different shadings of the carving.
Carat The term Carat is used as a standard unit of measurement of the weight of most gemstones including diamond. The word comes from the carob beans which are known for its consistent weight and was used in ancient times to measure gemstones. One carat (ct.) equals 200 milligrams, or 0.2 grams (1/5 of a gram), or 1/142 of an ounce. There are 100 points in a carat. If all other factors are equal, the more a stone weighs, the more valuable it will be. It is sometimes incorrectly spelled ‘Karat’, but Karat refers only to the fineness of pure gold and gold alloys.
Carving Carving refers to the cutting of decorative objects from a larger stone.
Center Stone The center stone is a main stone placed in central position in a piece of jewelry item with multiple stones. In a ring with one stone only, the center stone is also called the solitaire.
Channel Setting A setting style or method in channel form where no metal is displayed between stones and these stones are held in only by a slight rim which runs along the edges of the channel.
Chatoyant The term chatoyant is used for those stones that have ability to display or reflect a cat’s eye effect. This effect is caused by the precise occurrence of slight inclusions. A chatoyant gem exhibits a changeable silky luster as light is reflected within the thin, parallel, fibrous bands.
Choker A choker is a type of necklace usually made of pearls that fits tightly around the neck. It comes in 14 to 16 inches in length.
Citrine Citrine is a variety of mineral Quartz and available in colors like light yellow, lemon yellow, amber-brown and brilliant orange. This radiant gemstone gets its name from the French word ‘Citrin’, meaning ‘Yellow’. Citrine is known as a tough gemstone with 7 points on Mohs hardness scale and with good durability. This gemstone is mainly found in South America, Brazil, Madagascar, Argentina, Russia, Scotland and Spain.
Chip A curved break or absence of a tiny piece of a gemstone, caused by normal wear and tear, or by cutting.
Clarity Clarity is one of the main value factors of a gemstone which describes the absence or presence of flaws inside or on the surface of a gemstone. Gemstones are graded on a scale from Flawless (no inclusions or blemishes visible under 10x magnification) to Included (eye visible inclusions or blemishes). If other factors are equal, flawless stones are most valuable.
Claw Claw is a style of setting used to hold gemstones in place. It is also known as collet and consists of a ‘Bezel’ and ‘Prong’.
Cleavage The tendency of crystalline minerals to break in one or more definite directions, producing more or less smooth surfaces. A cleavage may be caused by inherent internal strain or by a sharp blow. Cleavage is one of the two methods used by stone cutters to split gemstones in preparation for the cutting process. The other method is sawing.
Closed Setting Closed setting is a style of setting in which back of the gemstone is not exposed and usually stone’s back is covered by metal.
Cloud A group of a number of extremely tiny white inclusions which gives a ‘cloudy’ or ‘milky’ appearance under 10X magnification. These clouds cannot be seen with the naked eye and generally does not significantly impact a gemstone’s clarity grade.
Collet Collet is a style of setting used to hold gemstones in place. It is also known as claw and consists of a ‘Bezel’ and ‘Prong’.
Color Color is the most important criteria in determining the value of a gemstone. Color is measured by tone and hue in a gemstone. In gemstones, color is more significant than clarity / cut and even subtle differences in hue can make a lot of difference in valuations.
Color Change Few gemstones distinctly change their color when viewed under two different light sources. This feature is commonly found in Alexandrite, Sapphire and Color Change Garnet.
Color Grading A system of grading gemstones color based on their hue or tone. Usually a well distributed hue is considered best for a gemstone.
Color Enhancement Color enhancement is the improvement process of a gemstone’s color mainly by irradiation and HPHT (High Pressure, High Temperature).
Composite Gemstone It refers to a gemstone which is assembled from several pieces, often used to imitate a gem.
Corundum Corundum is a hard mineral that exists in the form of colored crystals, such as Rubies and Sapphires.
Crown The upper portion of a cut gemstone above the girdle which surrounds a large flat area on top known as table.
Cryptocrystalline This term is used for a mineral structure in which crystals are very small and due to that they are not even distinguishable through a microscope.
Crystal A crystal is a solid material that has a definite internal atomic structure. Its atomic stricture produces a characteristic external shape as well as physical and optical properties.
Crystal Structure Crystals are divided in to seven groups on the basis of specific set of angular, geometrical and symmetrical specifications. All crystalline gems can be classified in one of seven groups based on the above specifications. These groups are cubic, tetragonal, hexagonal, trigonal, orthorhombic, monoclinic and triclinic.
Culet The smallest facet, at the bottom of most round or brilliant cut stones, is known as culet. Its purpose is to protect the tip of the pavilion from being chipped or damaged. Most modern shapes have either no culet at all, or a small or very small culet.
Cultured Pearl A pearl cultivated by an artificial process that imitates the organic process by which a natural pearl is created. An irritant such as a bead, grain of sand, or piece of mantle tissue is inserted manually into the body of a mollusk and becomes the nucleus of a pearl, once that mollusk secretes nacre to cover the irritation.
Cushion A shape of gemstone, which ranges from square to rectangular and it has rounded corners and larger facets to increase its brilliance. Cushion Cut stones are also known as “pillow cut” stones.
Cut Cut refers to the geometric proportions and finish of a gemstone. It is one of the most important factors in determining gemstone’s sparkle and brilliance. The stone should be symmetrical in all dimensions so that it will appear balanced, and so that its facets will reflect light evenly, which will provide good brilliance to stone.
Cutter The person who cuts and polishes rough gemstones and converts them into finished gemstones.
Cutting The process of cutting, grinding or polishing rough gemstones and converting them into finished ones.
CZ CZ denotes cubic zirconium, a widely used simulant, an imitation for a natural gemstone including diamond. But CZ is easily detectable by it’s 80% higher weight than a normal stone of the same proportions or by thermal conductivity testing.
Deep This usually means a gemstone which has been cut too deep. This deep cut maximizes weight but sacrifices brilliance.
Depth The height of a gemstone from the table to the culet which is measured in millimeters.
Depth Percentage The depth percentage, which expresses how deep the gemstone is in comparison to how wide it is. In other words, the depth of the gemstone is divided by the average width. This depth percentage of a gemstone is important to its brilliance and value. The pavilion should be deep enough to allow light to bounce around inside the gemstone and be reflecting out to the eye at the proper angle.
Diameter The width of the gemstone, as measured across the widest part of the girdle.
Diamond The word “diamond” comes from the Greek word “Adamas”, meaning “Unconquerable”. Diamond is composed of carbon that crystallizes in the “cubic,” or “isometric,” crystal system. It is the hardest known substance in the world (10 on Mohs’ scale). The Diamond is uniquely resistant to damage by heat or scratching, and can be cut or polished only by another diamond. It occurs in colors ranging from colorless to yellow, brown, orange, green, blue, and violet.
Dichoric This term refers to a gemstone that displays a different color or shade, which is other than the original gemstone’s color, when viewed from different directions or angles.
Dispersion Dispersion is the ability of a gemstone, to separate white light into the colors of the spectrum. It is also called the stone’s fire.
Double Refraction This term is used when each ray of light is split in two as it enters in a non-cubic mineral.
Doublet Doublet is a composite stone which is made of two components, usually cemented or glued together with a clear adhesive.
Drop Cut A drop cut or briolette is a pear-shaped cut gemstone with triangular facets on top. This type of stone makes a nice pendant.

 

Emerald Emerald, a variety of mineral Beryl, is one of the most fascinating and beautiful gemstones available in various shades of green color. The name of this remarkable gemstone comes from Greek ‘Smaragdos’,meaning ‘Green Stone’. Deep green is the most desired color in emeralds. Its hardness makes it very tough and durable which comes in between 7.5 to 8 on Mohs hardness scale and it is mainly found in Columbia, Brazil, Zimbabwe, South Africa, Afghanistan and USA. Flawless emeralds are very uncommon, and are noted for their great value, sometimes even more than diamonds.
Emerald Cut Emerald Cut gemstone is a square or rectangular shape stone with cut corners. This is also known as Step Cut because it has rows of facets, usually 48 to 50, that resemble a staircase. Due to its larger, more open table, this shape highlights the clarity of a gemstone but with fewer facets, this shape brings less brilliance than the other shapes.
Enamel Enamel is a powdered colored glass fused onto the surface of the piece of jewelry. It is a soft material and can be easily cracked or damaged. This should not be used on jewelry pieces, which are exposed to daily wear.
Engraving Engraving is a method of surface decoration in which a design is etched or engraved with a sharp tool.
Enhance,Enhanced,
Enhancement
Enhance or enhancement is the process to improve a gemstone’s color or clarity by using various methods like heating and oiling.
European Cut A European version of ‘ideal’ cut which was used and preferred in Europe although it was never adopted as a common form of cutting. In this cut, gemstone‘s proportions were worked out mathematically for light falling perpendicularly on the crown.
Extra Facet An additional facet placed onto a gemstone, usually to remove a small surface blemish. This extra facet is not required by the cutting style and symmetry.
Eye Clean A term used in the jewelry industry to describe a gemstone with no blemishes or inclusions that are visible to the unaided eye.
Face A term used for flat or plane surface that make up the exterior form of a crystal.
Facet A plane, polished surface on a gemstone which allows light to enter in a stone and reflect off through different angles.
Faceting Faceting is the process of placing facets on a gemstone. The shape and number of the facets give the stone its style of cut.
Fancy Cut, Fancy Shape Any shape of gemstone other than the round brilliant shape is known as fancy cut or fancy shape. It includes marquise, emerald cut, heart shape, pear shape, etc.
Fancy Diamond It is a Diamond with intense body color which is other than transparent stone with low color grade. Colored or fancy diamonds are very rare and valuable. Fancy diamonds are available in various colors like blue, pink, purple, red etc.
Fire Fire refers flashes of spectrum colors seen in a gemstone as the result of dispersion.
Flaw Flaw refers to any internal or external imperfection on a gemstone and usually includes scratch, feather, fissure, carbon spot, knot, etc.
Flawless Flawless is a term used for a gemstone that is without any internal or external flaw when viewed by a trained eye under 10X magnification.
Fluorescence An effect in many gemstones mainly in diamonds that makes them glow in ultraviolet rays or light. Stones can fluoresce in a number of colors mainly in blue. Fluorescence ratings include none, faint, slight, medium, strong and very strong. Faint to medium fluorescence is rarely detected under most lighting conditions which include sunlight also whereas strong or very strong fluorescence may make a stone appear ‘milky’ or ‘oily’ in such lighting conditions. Fluorescence is not dangerous to the stone or to its wearer. It is a unique and fascinating quality that occurs naturally in a number of gems and minerals.
Foiling A method of coating or placing silver, gold, or colored foil behind a gem in a closed setting to enhance its appearance as light is reflected by this. This is often done with rhinestones.
Fracture A breaking or chipping in a gemstone, which usually reaches its surface and is not in the direction of a cleavage plane.
Freshwater Pearl A freshwater pearl is an irregular shaped pearl that was harvested from a freshwater mussel (a mollusk). Usually these pearls are shaped like an uneven grain of rice, and are less valuable than oyster pearls. Biwa and Tennessee are the varieties of freshwater pearls.
Full Cut Brilliant A full cut brilliant is a gemstone usually with total of 58 facets, consisting of 32 facets and a table above the girdle and 24 facets and a culet below the girdle.

 

Garnet Garnet, which belongs to mineral quartz, is a family of stones having many varieties differing in color and in their constituents. This name is derived from its resemblance in color and shape to the seeds of the pomegranate. Garnet Stones are available in varieties named Grossularite, Pyrope, Almandine, Rhodalite, Andradite, Essonite, Tsavorite, Spessartite, Melanite, Allochroite, Ouvarovite and Demantoid. The most common color of Garnets range from light red to violet, but can also be white, green, yellow, brown and black except blue. Its hardness is between 7.5 to 8 on Mohs hardness scale and it is mainly found in Burma, Sri Lanka, South Africa, China, USA, Tanzania, Madagascar, India and Australia.
Gemologist A person with expertise in gemology is known as gemologist. There are many recognized courses available from various Gemological Institutes which offer study in gem identification, grading and pricing.
Gemological Institute of
America (GIA)
Gemological Institute of America (GIA) was established as a non-profit organization in 1931 by Roger Shipley. GIA maintains the highest standards for grading gemstones and it has one of the world’s most-respected and well-regarded gemological laboratories. GIA has developed and standardize the gemstone grading system that is used by nearly all other gem labs.
Gemstone A gemstone is a mineral or rock, which can be used in jewelry after cutting or faceting and polishing. Gemstones are diverse in their beauty and many gems are available in a stunning variety of colors. Most gemstones have little beauty in the rough state and they may look like ordinary rocks or pebbles in their rough form. After a skilled cutting and polishing of a gem, full color and luster can be seen. Gemstones are classified into two categories, precious and semi-precious, on the basis of their characteristics. Precious stones include diamonds, emeralds, rubies, and sapphires whereas semi precious stones are Alexandrite, Amethyst, Aquamarine, Citrine, Garnet, Iolite, Onyx, Opal, Pearl, Peridot, Tanzanite, Topaz, Tourmaline etc.
Geode Geode is a cavity within a rock which is a crystal line. It grows from inner surface to center in a gemstone. Usually geode found in Amethyst and Peridot stones.
Girdle Girdle is the widest part or outer edge of the gemstone and the dividing line between the crown and pavilion. The girdle can be rough (matt), faceted, polished or unpolished but a polished or faceted girdle doesn’t improve a gemstone’s grade. Most labs grade a girdle’s thickness, not its appearance and the descriptions of girdle thickness range as follows: extremely thin; thin; medium; slightly thick; thick; extremely thick.
Girdling Girdling is the process of giving a circular shape to a gemstone. In this process, a gemstone is held in a lathe, or in a cutting machine, and cut or shaped by another diamond or tool, called a sharp.
Gold Gold is a yellow precious metal used in most jewelry with various alloys.
Grade A recognized measure of an aspect of gemstone’s quality, mainly clarity, cut and color.
Grading The process of evaluating a gemstone, and allocating grades to it.
Grading Report A grading report or certificate is a statement, issued by an independent Gemological Laboratory, that at the time of evaluation, the gemstone in question has been examined, measured, and scrutinized by experienced gemologist and graders, using various gemological instruments, and determined to contain the characteristics as stated in the Report or Certificate. The grading report should accurately describe the proportions, weight, color, clarity, symmetry, polish and possible fluorescence seen in the gemstone.
Gram A unit of measurement of weight used to express the weight of a gem. One ounce equals approximately 28 grams and one thousand milligrams equals one gram.
Hardness The hardness of a gemstone refers it’s resistance to scratching on a smooth surface. Moh’s scale of hardness, which scales from 1 (very soft) to 10 (very hard), is useful for comparing the relative hardness of different gem materials. Diamond is the hardest known substance on Earth and it is graded 10 on Mohs’ scale of hardness. Hardness is directional in most gemstones.
Head Head refers part of the setting that holds the center stone or solitaire in place.
Heart Cut The Heart shaped gemstone is essentially a pear-shaped with a cleft at the top and which typically contains 59 facets. Due to the complexity of the shape, skilled cutting is necessary to maintain the gemstone’s brilliance. Generally people prefer a heart shape stone for sentimental purposes. This shape is mostly used in pendants, but also suitable for most jewelry items.
Heat Treatment Heat treatment is the process in which heat is offered to a gemstone for the purpose of improving its color.
Hue Hue is an aspect of color which is a primary factor in viewing and grading gemstones.

 

Idiochromatic
Gems
The colors in these idiochromatic gems come from elements that are an essential part of their chemical composition. These gems generally have only one color, or show a very narrow range of colors. Peridot is an idiochromatic gem, which is always green, due to one of its essential elements, iron.
Ideal Cut Theoretically perfect cutting proportions and facet angles, calculated mathematically to produce maximum brilliancy consistent with a high degree of fire in a round brilliant cut gemstone. Ideal cut is also known as American Cut.
IGI
(International Gemological Institute)
IGI(International Gemological Institute) is an organization which offers a grading report for all gemstones. IGI has laboratories located throughout the world, including New York, Antwerp, Mumbai, Bangkok and Tokyo.
Igneous Rocks These are rocks that are formed from erupted volcanic lava or solidified magma.
Imitation Imitation gemstones can be anything that resembles a natural gemstone but does not have the same physical characteristics or chemical composition. These items are usually much less expensive than the natural forms. Imitation stones are often made of glass or plastic and most can be detected easily by a jeweler.
Imperfect An imperfect gemstone contains any external blemish or internal inclusion or flaw that is visible to the unaided eye or that has a serious effect on the stone’s durability.
Inclusion An internal imperfection or characteristic which reduces the clarity or brilliance of a gemstone. Common gemstone inclusions are feathers, crystals, fractures, needles, graining, pinpoints and cavities.
Inlay This term refers to a decorative feature of an item of jewelry. An inlay is a piece of material (usually stone or glass) that is partially embedded in another material (usually metal) and these two materials make a level surface.
Intaglio Intaglio is a style of carving in which the design is carved into the surface of an engraved stone so that the rim shows the highest portion.
Internal Graining A gemstone which contains internal irregular crystal growth is known as internal graining. It may appear milky like faint lines or streaks.
Iridescent An iridescent material displays many lustrous, changing colors caused by the reflection of light due to inclusions in gemstones.
Jade Jade is a semiprecious stone, which is often used to describe jadeite and nephrite both as these two are similar in appearance and use. It is available in varieties of shades like green, light purple, yellow, pink, creamy white etc. Although this stone is found at many places but the best quality jade comes from Myanmar (formerly Burma). Jade is quite a hard stone with 6.5 to 7 on the Mohs scale and used in many jewelry items.

 

Karat, Karat Weight Karat is the American spelling of carat which is now only used for gold or gold alloys weight whereas English spelling carat is used in respect of weight of gemstones including diamonds. Karat is always based on pure 24 karat gold and if a jewelry item contains 18 karat gold that means it has eighteen parts pure gold and six parts other metal alloys.
Lapidary Lapidary is a skilled craftsman who cuts and polishes gemstones to their finished state.
Loupe Loupe is a French word for magnifying glass. It is a small magnifying lens used to examine gemstones. 10X magnification is the standard.
Luster The quality of reflected and refracted light from the surface of a gemstone or pearl. Luster is mainly dependent on stone’s surface (polish) and the reflective index of the mineral. Luster can be described as: adamantine, pearly, greasy, metallic, silky, resinous, vitreous, earthy (also known as dull) and waxy.

 

Make Make is a trade term referring to the proportions, symmetry and polish of a gemstone.
Marquise Cut The Marquise Cut is a traditional shape having elongated ends at both edges. The pointed ends make this shape the most fragile and the most expensive of brilliant style cuts. It has a total of 56 facets and construction of facet requires a lot of experience and delicacy of the sharp points demand utmost precaution. Now-a-days this shape is very popular for engagement rings.
Matrix Matrix is a rock in which gemstones are found. It is also referred as the host rock or parent rock.
Melee This term is used to describe small brilliant-cut diamonds under .20 carat. Generally, these small diamonds or gemstones are used to embellish mountings, setting or larger stones.
Metamorphic Rock These are rocks that have been changed by heat and/or pressure to form new rocks consisting of new minerals.
Millimeter The unit of measurement, which is used to determine a pearl and gem’s diameter, equal to about 0.04 inch.
Mine A place where gemstones are extracted from the ground by using various methods of mining like open cast, deep pit etc.
Mineral Mineral is a naturally occurring, inorganic element of the Earth with a consistent atomic structure and chemical composition.
Mixed Cut A mixed cut refers to a cut in which the style of the facets above and below the girdle are different. A standard mixed cut is brilliant cut above and step cut below.
Modern Brilliant
Cut
It is a round brilliant cut unless otherwise stated normally with 58 facets including the culet and polished using relatively modern theory. This shape is considered as ideal for a diamond because it maximizes a stone’s sparkle and brilliance.
Modified Brilliant
Cut
A cut in a shape or style other than round brilliant cut, such as oval, pear, marquise, heart, princess, radiant, or baguette.
Mohs scale It is a ten point scale to find mineral hardness which is devised by Friedrich Mohs, a German mineralogist, in the 19th century. The diamond is the hardest of all known natural substances and it scores 10 on Mohs Scale.
Mother of Pearl The iridescent lining of an oyster shell, often used as a nucleus for a cultured pearl.
Mounting The process of making a ring or other piece of jewelry into which gemstones will be set.
Natural A small portion of the original surface of a rough gemstone left by the cutter when polishing and faceting a gemstone and which is frequently on or near the girdle. This is generally the sign of a cutter attempting to maximize the weight retention of the rough gemstone. Usually naturals do not affect the clarity grade and in most cases, they are undetectable to the naked eye.
Natural Gemstones These have been formed in natural environment with no interference by human. They form in a variety of ways in many different environments from many different chemical compounds. By the time they appear in our jewelry they’ve been cut or polished, but they’ve not been treated or altered in other ways.
Natural pearl A pearl that forms naturally, in an oyster, is known as natural pearl. When a grain of sand or other small object enters in the shell and the oyster is unable to eject the object then the oyster will coat the object with layers of nacre to form a pearl. There is no way to determine if an oyster contains a pearl, so to create a dependable pearl supply, the culturing process was invented.

 

Old European Cut The earliest known form of brilliant cut diamond with a very small table, a heavy crown, and usually great overall depth. This is also known as old mine cut.
Onyx Onyx is a beautiful gemstone composed of chalcedony (a variety of quartz) and available in colors like black, white, black with white bands, red, brown etc. Onyx which is available in a red, brown or reddish brown color is known as Sardonyx. The bands that are found on this stone run parallel and are consistent. It is extremely similar to Agate, another variety of quartz. Agate bands are round or circular and are not consistent. Its hardness in between 6.5 to 7 on Mohs hardness scale and it is mainly found in Madagascar, India, Brazil, United States, Pakistan and Sri Lanka.
Opal The name Opal is derived from three sources: Sanskrit ‘Upala’, Latin ‘Opalus’, and Greek ‘Opallios’. All three of these words mean the same thing – precious stone. Opal is made from sand and water. It has the same chemical formula as quartz with the addition of 3 to 10 % water content. This is a very popular gemstone, mainly due to its wonderful variety of rich and beautiful colors like black, white, gray, yellow, red, orange and colorless. High quality opals have an extraordinary feature of opalescence in which light reflects and bounces around the very small structures of the stone, giving it a wonderful aura and sometimes iridescence. The group of fine Opals include quite a number of wonderful gemstones which are differentiated on the basis of the variety, place of occurrence, and color of the main body, into Dark or Black Opal, White or Light Opal, Milk or Crystal Opal, Boulder Opal, Opal Matrix, Mexican and Fire Opal. Its hardness in between 5 to 6.5 on Mohs hardness scale and it is mainly found in Australia, Brazil, Mali, Japan, Russia, USA and Mexico. Australia is the major supplier of Fine Opals and almost 95 per cent of all Opals come from Australian mines.
Opalescence Opalescence is a kind of light play that happens with certain high quality stones. In these stones, light reflects and bounces around the stone structures which give them a wonderful aura and sometimes a milky blue form of iridescence.
Opaque Opaque refers to the transparency of a gemstone. Generally opaque stone does not transmit light as it is so thick with inclusions or flaws and due to that light is blocked from passing through the gemstone.
Optical Effects Some gemstones exhibit extraordinary optical effects known as phenomena. These rare and beautiful effects very often add value to gemstones. Some of these popular phenomena are Chatoyancy (cat’s eye effect), Asterism (star effect), Color Change, Aventurescence and Iridescence.
Organic Gem Gemstones made by or derived from living organisms are known as organic gems. These include pearls from oysters, amber from tree resin etc.
Oval Cut The Oval Cut is a beautiful Fancy shape which offers great brilliance and fire through its 56 facets. This is an elongated version of round cut, provides the same brightness which comes from a round brilliant shaped gemstone.
Parti-colored Gems These are crystals that are made up of different colored parts. Stones made up of two colors are known as bicolor and made up of three colors are known as tricolor whereas sometimes these are available in more than three colors also. In some cases, Tourmaline exhibits as many as 15 different colors or shades within one crystal.
Pave An attractive style of jewelry setting in which numerous small stones are mounted as close together as possible to create a sparkly stone shell. The pave setting is very popular with diamonds and this setting style covers the whole piece of jewelry with diamond crust and conceals the metal under it.
Pavilion Pavilion is the lower part of a gemstone, below the girdle.
Pear Cut The Pear Cut is a fancy shape stone that looks like a teardrop due to its single point and rounded end with 56 to 58 facets. This shape is popular for its uniqueness and brilliance.
Pearl A Pearl is an organic gem, produced when certain mollusks, primarily oysters cover a foreign object with beautiful layers of nacre. A good sized Pearl can take between five to eight years to form, which is usually the entire life of the oyster or mollusk. There are two types of Pearls: Natural Pearls, formed inside wild oysters, practically impossible to find nowadays, and Cultured Pearls in which the production of the pearl is artificially induced. For producing cultured pearls, shell beads are placed inside an oyster and the oyster is returned to the water. When the pearls are later harvested, the oyster has covered the bead with layers of nacre. The finest Natural Pearls are fished almost exclusively from the Persian Gulf and the China Sea, while the best cultivated ones come from Japan, Korea and more recently Australia. Its hardness in between 2.5 to 4.5 on Mohs hardness scale and should be handled with care. Pearls are usually white, sometimes with a creamy or pinkish tinge, but may be tinted with yellow, green, blue, brown, purple, or black. Pearls are available in different shapes: round, semi-round, button, drop, pear, oval, baroque, and ringed. Perfectly round Pearls are the rarest and most expensive. Fine Natural Pearls are much more expensive and rare to find than Cultured Pearls.
Peridot Peridot, a variety of mineral olivine, is a very old but still very popular gemstone. Peridot is formed deep within the earth under tremendous heat and pressure. The color of peridot is an integral part of its structure. Chemically peridot is an iron-magnesium-silicate and its intensity of the color depends upon the amount of iron contained by it. It is available in only one color shade with colors like yellow green, olive and brownish green. This gemstone is in fact identified by three names, Peridot, Chrysolith and Olivin. Its hardness in between 6.5 to 7 on Mohs hardness scale and it is mainly found in Australia, Mexico, Sri Lanka, South Africa, Tanzania, China, Burma, Arizona, USA, Pakistan and Afghanistan.
Platinum Platinum is a silvery gray precious metal often used for setting or mounting high quality gemstones.
Pleochroism Pleochroism refers to the ability of certain gems to display two or more colors when viewed from different directions.
Point A unit of measurement which is used to describe the weight of gems where one point is equivalent to one-hundredth of a carat. For example, a 1/2 carat diamond weighs 50 points.
Polish Polish is considered as smoothness of the surface of a fashioned stone in which optical reflection is maximized. Generally a polished stone does not show visible wheel marks or burn marks under 10X magnification. Polish is an indicator of the quality of stone’s cut which is graded as Ideal, Excellent, Very Good, Good, Fair or Poor.
Polishing The process of polish which converts a stone’s rough or irregular surface to a smooth surface by using various methods.
Precious,Precious Stone The term precious is used for stones as well as metal. Stones those are highly valuable for their hardness and rarity, are known as precious stones. Precious stones include diamonds, emeralds, rubies, and sapphires.
Princess Cut The princess cut is a fancy shape gem which has pointed corners and square in shape. The ideal princess cut will have length to width ratio as close to 1.00:1.00 as possible. Princess cut stones can range from this perfect square through to almost rectangular.
Prong Setting Prong setting is the most frequently used method of setting gemstones into jewelry. This setting usually consists of four or six small metal tips or claws to hold the stone tightly. This setting allows maximum amount of light to enter in a stone from all angles and because of this, stone appears more brilliant and larger than its actual size.
Purity Purity is also known as clarity which describes the absence or presence of flaws inside or on the surface of a gemstone. For diamonds, purity is graded from F (flawless) to I3 (included 3) whereas for other colored gemstones, purity is classified into three ‘Types’. Type I colored stones include stones with very little or no inclusions, Type II colored stones include stones that often have a few inclusions whereas Type III colored stones include stones that usually always have inclusions.

 

Quartz Quartz is the most common mineral on earth. It is a crystalline mineral that comes in many forms.
Radiant Cut The Radiant Cut is a fancy shaped rectangular or square gemstone with cut corners. This shape comes with 62 to 70 facets and offers the elegance of the emerald shape with the brilliance of the princess shape. Trimmed corners are the signature of this shape, and they help to make the radiant cut a popular and versatile choice for jewelry.
Reflection The term reflection is used for important optical effect where light bounces or returns once it strikes the surface of a gemstone.
Refraction The term Refraction is also used for optical effect where light deviates or changes its direction once it enters in a gemstone.
Refractive Index (RI) When light meets the surface of a polished gemstone, some of the light is reflected, whereas most is absorbed. This entered light in the gem slows down and is bent from its original path due to the difference of density between air and gemstone. This process is known as refraction. This refraction varies from gem to gem depending on density and can be measured and used to help identify the gem type. This measurement is known as refractive index (RI).
Refractometer Refractometer is a device that is used to measure the refractive index of gemstones.
Rough The term rough is used for any uncut or unpolished gemstone.
Round Brilliant Cut The round brilliant cut is one of the most traditional and popular shapes. It has 58 facets which offer great brilliance and stability. These 58 facets include 1 table, 8 bezel facets, 8 star facets, 16 upper-girdle facets on the crown, 8 pavilion facets, 16 lower-girdle facets, and usually a culet on the pavilion, or at bottom. This cut is considered as ideal for a diamond because it maximizes a stone’s sparkle.
Ruby Ruby is the red variety of the mineral corundum and known for its magnificent color, excellent hardness and outstanding brilliance. Only red corundum is entitled to be called ruby, all other colors being classified as sapphires. This stone is available in colors like bright red, brownish-red, purplish-red, dark red and blood red. The name ‘Ruby’ comes from Latin ‘Rubens which means ‘Red’. In Sanskrit, the ruby is called ‘Ratnaraj’, meaning ‘the king of precious stones’. This gemstone has excellent luster, rarity and durability. Its hardness is 9 on Mohs hardness scale and it is mainly found in Burma, Thailand, Sri Lanka and Tanzania. Transparent rubies of large sizes are even rarer than diamonds.

 

Sapphire Sapphire is a variety of the mineral corundum and represents all the colors except red corundum, which is ruby. Its physical and chemical properties are virtually similar to properties of ruby. Blue is the main color of the sapphire whereas this gemstone is also found in colors like yellow, green, orange, pink, gray, colorless, black, brown, and purple. The word ‘Sapphire’ in its plain context refers only to blue sapphire, unless a prefix color is specified. Sapphire is one of the most desirable gems due to its color, hardness, durability, and luster. Its hardness is 9 on Mohs hardness scale and it is mainly found in Sri Lanka, Thailand, Burma, Australia, India, Brazil and Africa.
Sardonyx Onyx which is available in a red, brown or reddish brown color is known as sardonyx.
Saturation A color’s position in a gemstone on a neutral to vivid scale.
Secondary Deposit Minerals and/or gemstones that have been separated from their original host rock, usually due to effects of weather, and deposited elsewhere. An alluvial deposit is an example of a secondary deposit.
Semi Precious,
Semi Precious
Stone
Stones those are valued for their beauty and not covered under any one of the four ‘Precious Stones’, Diamond, Emerald, Ruby or Sapphire, are known as semi precious stones. Semi precious stones are available in all price ranges from low priced to high priced. Semi precious stones are Alexandrite, Amethyst, Aquamarine, Citrine, Garnet, Iolite, Onyx, Opal, Pearl, Peridot, Tanzanite, Topaz, Tourmaline etc.
Semi-mount A style of jewelry setting that has the side stones already mounted, but which contains an empty set of prongs which are intended to mount a center stone as per the customer’s choice.
Setter Setter is the person who puts gemstones into jewelry mounts.
Setting Setting is the process of fixing a gemstone into a mount to create a piece of jewelry.
Shape A gemstone cut by shape describes the outline of the stone and pattern of the facet arrangement. Gems are available in various shapes like Modern Round Brilliant, Emerald, Princess, Heart, Oval, Pear etc. Round brilliant is the most popular shape for all jewelry items. All other non-round shapes are called fancy shapes.
Silver Silver has been known and used for thousands of years and it is considered as one of the three precious metals along with gold and platinum. Pure silver is very soft metal with its lustrous white color. Silver was used as jewelry metal well before the development of white gold alloys, and before platinum could be isolated.
Simulant,Simulated Stones Simulated stones can be anything that resembles a natural gemstone but does not have the same physical characteristics or chemical composition. These items are also known as imitation stones and usually much less expensive than the natural forms. Simulated stones are often made of glass or plastic and most can be detected easily by a jeweler.
Single Cut A very small round stone with only 17 or 18 facets, instead of the normal 57 or 58 facets of a full cut round brilliant. These facets include 8 bezel, 8 pavilions, a table and sometimes a culet facet.
Solitaire A ring or any other piece of jewelry containing a single diamond or other gem. This style is very popular in rings.
Sparkle Sparkle is the combination of gemstone’s fire and brilliance.
Specific Gravity Specific gravity of a gem is an indication of its density. It is calculated by comparing the gemstone’s weight with the weight of an equal volume of water. The greater the specific gravity of a gem, the heavier it will feel.
Step Cut Step cut is a style of faceting arrangements which is named because of its broad, flat planes that resemble stair steps. In this style of arrangement, there are three concentric rows of facets arranged around the table and, on the pavilion, there are three concentric rows arranged around the culet.
Stone A general word for any gemstone including diamond.
Symmetry Symmetry is an important aspect of the gemstone cutting process which refers to the balance of the outline shape and alignment of the facets. It is graded as Ideal, Excellent, Very Good, Good, Fair or Poor.
Synthetic A synthetic gemstone shares a natural stone’s physical, chemical and optical qualities, but it is created in a laboratory. Some modern synthetic gemstones look more natural and are more difficult to identify, but an experienced jeweler or gemologist can usually detect them.
Table Table is the largest and flat facet which is placed on top of a gemstone. Most of the light enters and exits from this part of a gemstone.
Table Percentage The table percentage is a comparison of the diameter of the table facet to the diameter of the entire gemstone.
Tanzanite Tanzanite is a blue variety of the gemstone zoisite and named after the East African state of Tanzania, the only place in the world where it has been found. It is a trichroic gem which displays three layers of color. The colors dark blue, green-yellow and red-purple can be seen. Tanzanite is a beautiful gemstone, known for its brilliance but on the other hand it is a delicate gemstone which comes in between 6 to 7 on Mohs hardness scale.
Tension Setting A method of setting gemstones using only the springiness of the mount to hold the stone firm. Although it looks quite spectacular but is very unsafe and should be avoided.
Tone An attribute of color which determines its lightness or darkness of shading and important in grading gemstones.
Topaz Topaz, a member of quartz family, is a beautiful gemstone that most commonly is found in yellow color. It is also available in various other colors like blue, brown, green, orange, pink, red, white, gold, colorless etc. The name topaz is derived from the Sanskrit word ‘Tapas’, meaning ‘Fire’. Topaz, with 8 on Mohs hardness scale, is considered tough and durable gemstone but still is not an invincible stone. It cracks and chips easily than many other gemstones. It is mainly found in Brazil, Sri Lanka, Burma, Nigeria, USA, Australia, Madagascar and Mexico.
Tourmaline Tourmalines are gemstones with deep brilliance and an incomparable variety of colors like black, red, pink, blue, green, grey and yellow. These Gemstones are mixed crystals of aluminium boron silicate with a complex and changing composition. The name tourmaline comes from the Singhalese words ‘tura mali’, means something like ‘stone with mixed colors’. Tourmalines with different colors have different names. It comes in between 7 to 7.5 on Mohs hardness scale and it is mainly found in Brazil, Sri Lanka, South Africa, Nigeria, Zimbabwe, Kenya, Tanzania, Mozambique, Madagascar, Pakistan, Afghanistan and USA.
Translucent Translucent is used to describe stones that allow light to pass through them, but the light is diffused.
Transparent Transparent is used to describe stones that are clear and transmit light without any diffusion so that objects can be seen through the stones.
Treated Gemstone,
Treatment
Treated gemstones are those which have been processed in some way to enhance their color or clarity. A number of treatment techniques are used to improve the color and appearance of natural and synthetic gemstones. Heat treatment is the oldest method whereas other techniques include bleaching, dying, laser drilling, fracture filling, high pressure high temperature (HPHT), annealing, irradiation, and surface coloration.
Trichoric Trichoric refers to a gemstone that displays three different colors or shades when viewed from different angles or directions.
Trilliant Cut, Trillion Cut The Trilliant Cut is a triangular fancy shaped gemstone which is also known as Trillion Cut. This shape of gemstone looks unusual and displays a very sharp brilliance or fire. It may either have pointed corners or more rounded corners.

 

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