Abrasions: Minuscule nicks along facet junctions, producing white hazy lines instead of sharp facet edges.

AGSL: The American Gem Society Laboratories, an industry leader in diamond grading.

AGS: The American Gem Society, founded and supported by approximately 1,000 high-end jewelers. They are recognized as one of the top gemstone grading organizations.

AGTA: The American Gem Trade Association, an industry leader in diamond grading.

Allochromatic: Refers to the coloring by minor impurities of stones, which, if pure would be colorless.

Alloyed: Refers to the "mixing" of different metals with Gold to increase hardness and/or change the color. Two or more metals are melted together, resulting in a compound metal, or alloy.

Anneal: A heating enhancement process used with color gemstones. The term originated with the Independent Gemological Laboratories (IGL), an industry leader in diamond grading specializing in larger stones. Also, a heating process to soften precious metals.

Appraisal: A formal evaluation process through which the value of a diamond (or any item) is determined and documented. It takes into account every aspect of a diamond's characteristics and dimensions, and serves as the basis for determining the proper insurance coverage rate for the item.

Assay: A test of the purity of an alloy. A tiny piece of metal is scraped from the piece and the percentage of gold or silver is determined.

Asscher: A unique, square-shaped cut diamond with rectangular facets.

Avoirdupois: A basis for weighing things other than jewels and precious metals. The unit is a pound containing 7000 Troy grains. The Troy pound contains 5760 grams.

Azured: In blanks for wedding rings, or other jewelry made to be set with stones, the settings are said to be "azured" when each has the hollow for the pavilion of its stone formed into a square; the space below the girdle of the stone has the form of a truncated pyramid. The azure allows more light into the stone, enhancing its reflective qualities.

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B & S Gauge: Standard American gauge used for measuring thickness of wire and sheet. The lower the number gauge, the thicker the material (e.g. 30 gauge = .010", 18 gauge = .040")

Baguette shape: A rectangular shaped diamond with rows of step-like facets. If the baguette's two long sides taper inward, it is called a tapered baguette.

Bail: A finding, connected to pendants or stones worn as pendants to accommodate a chain, cord or thong.

Band: A ring that is made from a thin, flat, ribbon-like strip of material (usually metal).

Bar channel setting: Similar to the channel setting, it is a circular band of diamonds that holds each stone in by a long thin bar, shared between two stones.

Barion cut: A diamond cut with a traditional step cut crown and a modified brilliant cut pavilion. A square barion cut diamond has 61 facets, excluding the culet.

Base metal: Metals which are commonly used to alloy gold jewelry, e.g. copper, silver, zinc, nickel, platinum and palladium.

Basket setting: A fancy setting of various shapes with numerous side piercings that provide a basketwork or lacy appearance.

Bead setting: A method of diamond setting in which the stones are set flush in a strip of metal. The stones are held by the beads, which are raised by the diamond setter from the surrounding metal.

Bearding or girdle fringes: The outermost portion of the diamond, called the girdle, can develop small cracks that resemble whiskers during the polishing process.   These whiskers, or bearding, can sometimes be removed, if not too dramatic, with slight re-polishing, and if the weight allows.

Bevel cut/Biseau cut: A stone cut with a large table and the edges beveled by a single facet; the bottom may be cut normally, or it may be the same as the top, in which case it is known as double bevel cut.

Bezel facets: Also called kite facets, because of their shape, bezel facets are cut along the crown or top of the diamond or gemstone.

Bezel setting: A setting in which a metal rim holds the stone and completely surrounds the gem. Bezels can have straight edges, scalloped edges or can be molded into any shape to accommodate the stone.

Black-centered stone: A lumpy diamond with an overly deep pavilion.

Black diamond: A term used for truly black diamonds and for carbonado.

Blemish: Any type of flaw on the surface of a diamond or other gemstone.

Blue gold: An alloy of light blue color usually composed of iron and gold. Not commonly used in making jewelry because the iron causes a very brittle alloy.

Bowtie effect: Found in marquise, oval, pear and some heart shaped diamonds. The bow tie looks like two dark triangle shapes joined at the point in the center of the diamond. This is caused by light leaking from the stone and is considered to be a liability if it is prominent. It can be caused from an overly deep pavilion.

Box setting: A setting for a stone in a ring, the top edges of the "box" being burnished over the edges of a stone to hold the stone in the setting.

Brazing/Soldering alloys: Precious metal alloys designed to melt before the alloy that a jeweler will join together. The solder is heated to a liquid state and two pieces of metal are joined together.

Brilliance: The amount of light reflected through and out of a diamond. A stone's brilliance depends on two key characteristics of its cut: symmetry and polish.

Brilliant cut: The term for a cut with 58 facets. These cuts are scientifically found to reflect the most light from within the stone and often are considered to have the most brilliance of all cuts.

Bruise: A type of minor flaw on the surface of a diamond or other gemstone characterized by a root-like appearance (like a cracked windshield) inside the stone.

Bruted girdle: A girdle cut that leaves the girdle with a frostlike appearance.

Bubble: An apparent void; often they are included crystals of some foreign substance, but so colorless and so different in refractive index that they resemble cavities.

Bullion: 24K of fine gold or fine silver in bar, ingot or other form, as distinguished from coin.

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Cabochon: An unfaceted form of cutting where the stone is given a rounded, convex shape and cut high or low for best effect.

Canary diamond: A fancy diamond with a strong, pleasing yellow color.  

Carat (ct): One of the "4 C's," carat is the term used to define the measure of weight of a diamond. One carat is the equivalent of 200 milligrams. One carat can also be divided into 100 "points." A .75-carat diamond is the same as a 75-point or ¾-carat diamond.

Carat Total Weight: The total diamond carat weight of all the stones in a piece of jewelry.

Cavity: A tiny flaw, in the form of a hole, on the surface of a diamond or other gemstone. In higher-quality stones, these will not be visible to the naked eye.

Center stone: The premier, most centrally located and usually largest stone in a jewelry setting with multiple stones. In settings with only one stone, the center stone also is called a solitaire.

Centimeter: One hundredth part of a meter or 10 millimeters.

Centrifugal casting: A method of making small metal castings used in jewelry shops. Molds, filled with melted metal, are whirled by machinery so that centrifugal force crowds metal into the smallest spaces, producing work sharp in details.

Certification: This is a diamond grading report. There are many recognized gemological labs that can grade your diamond for a fee.

Certified gemologist: A title granted by the American Gem Society to jeweler members who have completed several advanced gemology courses and examinations.

Channel setting: Small grooves in a jewelry setting that help hold the stone in place. Used most frequently for wedding and anniversary bands, a channel setting will set the stones right next to each other with no metal separating them.

Chip: A flaw in a gemstone usually created by damaging contact with another surface or hard material.

Clarity: One of the "4 C's," clarity refers to the presence (or absence, ideally) of identifying characteristics, called inclusions, in the stone. Diamonds with no or few inclusions receive a higher rating for clarity and are more valuable than those with noticeable inclusions. The grades of clarity vary from F (Flawless) and IF (Internally Flawless) through to I (Included). Clarity scale I can be seen by the human eye without magnification.

Clasp: The mechanism on the end of jewelry bracelets and necklaces that manually opens and closes to firmly connect the two ends and hold the jewelry in place.

Cleavage: A tiny flaw, in the form of a crack, inside a diamond. Very minor cleavages will not affect the brilliance of a stone. Major cleavages can damage the diamond's structural integrity.

Cloud: A group of minute crystals, called pinpoints, which may form inside some diamonds. Very minor clouds are not visible to the naked eye and do not affect the brilliance of the stone or compromise its integrity.

Cluster setting: This setting surrounds a larger center stone with several smaller stones. It is designed to create a beautiful larger ring from many smaller stones.

Cobalt (Co): A silver-white metal, harder and stronger than iron or nickel. Used as an alloy in the making of steel and as a coloring material for many blue glasses which simulate gems.

Color: One of the "4 C's," color refers to the presence (or absence, ideally) of a particular color in a diamond. The scale ranges from D (colorless) to Z. An ideal diamond will have as little color as possible. The closer to white or "colorless" the stone appears, the more valuable it is. Fancy colors are not included in this color scale and are considered extremely rare.

Comfort fit: A type of jewelry band featuring a rounded inside edge--as opposed to a sharper edge-to eliminate pinching and improve its comfort.

Complexion: The presence or lack of blemishes on a stone's surface that define its appearance.

Concussion mark: A small bruise, usually outlined by minute cleavages in a four- or six-sided pattern, commonly found on most diamonds after wear.

Copper (Cu): Copper is a soft metal often used in jewelry. It is used in making bronze, brass, and gold alloys.

Critical angle: That angle beyond which all incident light is reflected, without escaping from the stone. Ideal cut diamonds use these angles to ensure maximum reflectivity or brilliance.

Crown: The upper facets of the diamond, above the girdle, leading to the table, or the top of a diamond.

Culasse: The pavilion.

Culet: The facet at the tip of a gemstone. It may be polished in some stones. The stone cutter may choose to make the culet a surface instead of a point.

Cushion cut: A mixed-cut diamond shaped like a square pillow.

Cut: One of the "4 C's," cut refers to the angles and proportions a skilled craftsman creates in transforming a rough diamond into a polished diamond. Based on scientific formulas, a well cut diamond will internally reflect light from one mirror-like facet to another, and disperse and reflect it through the top of the stone. This results in a display of brilliance and fire. Diamonds that are cut too deep or too shallow lose or leak light through the side or bottom, resulting in less brilliance and ultimately value.

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De Beers Consolidated Mines Limited: De Beers conducts the mining of about 45% of the world's gem and industrial diamonds, and the marketing of the vast majority of all newly mined rough gem and industrial diamonds through associated companies.

Deep cut: Cut refers to the angles and proportions a skilled craftsman creates in transforming a rough diamond into a finished diamond. When a diamond is cut too deep, it will lose or leak light through the bottom or sides. This results in less brilliance and value.

Depth: The height of a diamond, as measured from the culet to the table.

Depth percentage: The quotient derived by dividing a diamond's width by its depth. This formula is critical in determining a diamond's brilliance.

Diameter: The width of a diamond or other gemstone at its widest part, the girdle.

Diamond: A diamond is crystallized carbon. It is the hardest known natural substance. Diamonds grow in the earth more than 150 kilometers deep in the mantle and their growth rate may be highly variable depending on the local abundance of carbon, the temperature, the presence or absence of melt, and other factors. Many of the diamonds found at the surface of the earth or in mines are very old, perhaps 3 billion years. Diamonds are mined in their rough form and then cut and polished to reveal their brilliance.

Diamond grading reports: Appraisals of diamonds. There are many recognized gemological labs that can grade your diamond for a fee.

Dimensions: A diamond's width and height as they appear in the setting.

Dispersion: When light enters a diamond it reflects off the facets and the angles cut into the stone. This distribution of light is known as dispersion, or the display of the spectral colors.

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Enhancements: Procedures or treatments, such as oiling and heating, which are typically part of the cutting and polishing processes to increase the diamond's qualities. For a stone to be certified, these must be permanent and must not compromise the natural beauty of the diamond.

Emerald shape: A step cut gemstone that can be rectangular, square or even triangular, where the corners have been cut off for protection and easier prong setting.

Eternity ring/Anniversary band - A narrow band of platinum or gold set with a full or half circlet of diamonds and perhaps colored stones, given by husband to wife as a pledge of continued love, to mark the birth of a child, or a wedding anniversary.

Extra facet: A facet placed without regard to symmetry and that is not required by the shape of the diamond.

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Faceted girdle: A girdle that has been cut with facets.

Facets: These are tiny surfaces polished onto a rough diamond that give a finished diamond its shape. The way light interacts with these facets affects a diamond's brilliance and sparkle.

Fair cut diamond: Diamonds that simply fail to reflect a sufficient amount of light. In most cases, they are too shallow or too deep to meet the minimum standards of a good cut.

Fancy color diamond: A very rare and expensive type of diamond that may appear blue, green or yellow. These are the only diamonds actually made more valuable because of their color.

Fancy shapes: Any diamond shape other than round; e.g., marquise, square, emerald, oval, heart and pear.

Fancy yellow: Diamonds in the D to Z colorless category that are so yellow that they transcend the scale and become a classification all to themselves. When bright yellow, they can be as valuable as D colorless diamonds.

Fault: Anything which damages the appearance of a diamond, and thus lessens the value - flaws, scratches, chips, etc.

Feather: A tiny fracture inside a diamond that may be feather-like in appearance. It is a separation or break due to either cleavage or fracture, often white and feathery in appearance. Most feathers are insignificant and do not visibly affect the brilliance or compromise diamond integrity. Also called a fracture.

Fezels: Wispy, irregular white inclusions inside a diamond that was cut from a macle, or rough diamond.

Findings: Standardized parts of jewelry used in manufacturing and repair work, such as ear nuts, shanks, catches, lobster claws, settings, etc.

Fingerprints: A type of inclusion, or internal flaw, particularly found in corundum.

Finish: Finish is used to describe the exterior of the diamond. If a diamond is well polished, it has a very good finish.

Fire: Often a term used instead of "dispersion," it is the variety and intensity of rainbow colors seen when light is reflected from a diamond.

Fish eye: A noticable white circle that looks like a fish eye, present in some poorly cut diamonds.

Fishtail: The name for certain settings that have the shape of a fishtail in the side of the setting.

Fissure: An elongated cavity, usually the result of a cleavage opening to the surface of a diamond or gemstone.  

Flat ends: Thin diamond cleavages.

Flaw: An imperfection in a diamond, visible through a ten-power loupe.

Flawless: The top clarity grade in diamonds; without flaws; perfect.

F/IF Diamonds (Flawless/Internally Flawless): Diamonds in this category have no internal inclusions. They are extremely rare and highly valued. These stones are perfect.

Fluorescence: When exposed to ultraviolet light, a diamond may exhibit a more whitish, yellowish or bluish tint, which may imply that the diamond has a property called fluorescence. The untrained eye can rarely see the effects of fluorescence. Diamond grading reports often state whether a diamond has fluorescent properties. Fluorescence is not considered a grading factor, only a characteristic of that particular diamond. A synonym for fire.

Four C's: The term used to describe the four critical things to consider when buying a diamond: cut, color, clarity, and carat.

Fracture filling: In diamonds, fracture filling entails a molten glass filling that improves clarity. You can get a lot more stone for your money buying fracture-filled diamonds; the problem is that the treatment isn't always permanent. Get all enhancements clearly stated on your bill of sale.

Fracture: A crack on a diamond's surface. Also called a feather.

Full cut: A gemstone with 58 facets.

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Gemologist: One who completes recognized courses of study of gem materials and/or passes examinations that demonstrate his competence to identify and evaluate gem materials.

Gemology: The scientific, historical and legendary study of gem materials, as distinct from all the minerals scientifically studied in mineralogy.

Gemstone: A naturally occurring mineral found in the rocks of the earth, the chemical composition and internal atomic structure of which make it suitable for jewelry use:   color, clarity, hardness, rarity and availability.

GIA: The Gemological Institute of America (GIA), an industry leader in diamond grading.

Girdle: The band around the widest part of a diamond. It is usually the part of the diamond to which the setting is adhered.

Girdle width: The proportion of the girdle to the rest of the stone. Too thin a girdle leaves the stone susceptible to cracks and breakage, while a girdle too thick will have reduced brilliance and fire.

Gold (Au): A yellow-colored precious metal that is very soft when pure (24 Kt.). Gold is the most malleable (hammerable) and ductile (able to be made into wire) metal. Gold is alloyed (mixed with other metals, usually silver and copper) to make it less expensive and harder. The purity of gold jewelry is measured in karats.

Good cut diamond: This category represents the top 35% of diamond cuts. While they may still be quality diamonds, they will show a significant lack of brilliance. They are, however, considerably less expensive than the grades above them.

Grading: The process of evaluating a diamond's characteristics (most commonly its cut, color, carat and clarity) to determine its quality and value.

Graduated: The term used to describe an incremental change in the size of multiple gemstones within the same setting.

Gram: Unit of weight in the metric system, based on the weight of one cubic centimeter of water. One kilogram, or 1000 grams, = 2.2046 pounds. (31.103 grams = 1 Troy ounce).

Green gold: Gold alloy containing a relatively high proportion of silver. The higher the karat or quantity of gold, the better the green gold color.  

Growth or grain lines: These can be considered internal flaws, and can often be seen only by rotating the diamond very slowly. They can appear and disappear almost instantaneously. They appear as small lines or planes within the diamond.

Guard-ring: A thin ring, inconspicuous in appearance, worn on a finger in front of a valuable ring, to prevent the latter slipping off. Guard rings are often worn in pairs, with or without stones, on each side of a wedding ring.

Gypsy setting: This setting is predominantly used for men's jewelry. The band is one continuous piece that becomes thicker at the top. The top is dome shaped and the stone is inserted in the middle.

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Hair: A type of inclusion in a gem, resembling a hair.

Hardness: In reference to gems and minerals, the resistance offered to abrasion or scratching. Minerals are measured and numbered on a relative hardness scale, where the intervals between the numbers are very different (e.g. a diamond, the hardest, is far harder than the next mineral down the list).  

Head: The main part of a setting, including the "basket" and prongs, which holds the diamond in place.

Head shape: The shape of the setting's head, usually determined by the shape of the stone.

Head size range: The range of sizes of a diamond that can be mounted to a head. It is usually determined by carat weight.

Heart shape: A pear-shaped diamond with a cleft at the top.

Height: The estimated size of a diamond, measured vertically from the top.

Hook clasp: The part of the clasp that physically moves to lock it in place.

Hue: A descriptor of a diamond's color that indicates whether it is pure or shows the presence of another color.

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Ideal cut: An ideal cut diamond has the best combination of angles that allow light to enter the diamond and be reflected back, to create the best combination and brilliance and fire. Ideal cuts often create perfectly aligned arrows and heart patterns that can be seen under magnification.

IGL: The Independent Gemological Laboratories, an industry leader in diamond grading that specializes in grading jewelry set with large diamonds.

Illusion setting: This setting is more intricate than others in that it surrounds the stone to make it appear larger. The metal that surrounds the stone is usually faceted or polished white gold to enhance the diamond.

Imperfection: Any flaw, crack, carbon spot, cloud or other blemish of any sort observable in a gemstone, when the latter is examined by a trained eye under a 10-power magnifier.  

Inclusions: Identifying characteristics in a diamond, usually in the form of a blemish, scratch, air bubble or any other foreign material either inside the diamond or on its surface. Often referred to as "nature's fingerprints." They are what make a diamond so unique, as a fingerprint does for a person. These birthmarks are measured on a scale of perfection known as clarity. Some common names of inclusions include cloud, crystal, pinpoint and feather. The position of inclusions can affect the clarity of a diamond and therefore the value.

I1/I2/I3 (Inclusions visible to the unaided eye): These diamonds contain significant inclusions that are visible both under magnification and to the naked eye. Because "I" grades have inclusions that can be seen with the naked eye, we do not recommend that you buy these diamonds for an engagement ring.

Internal stress: Stress in a diamond or gemstone resulting from inclusions or other structural irregularities, visible through the polariscope.

Iridium (Ir): Iridium is a metal related to platinum. Iridium and platinum are frequently alloyed together, as the iridium increases the workability of the platinum.

Irregulars: A diamond shape classification, crystals of irregular shape with broken parts.

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Joint: An item of jewelry findings, soldered or screwed to a piece of jewelry, to form, with a pin, a hinge for the pin with which the piece is fastened to the clothing of the wearer.  

Karat: Indicates the amount of pure gold present in a metal. 18K yellow gold consists of 75% gold and 25% other metals; these are usually copper and silver. 14K yellow gold consists of 58% gold and 42% other metals.

Knot: A tiny crystal on the surface of a diamond. Very minor knots are not visible to the naked eye and do not affect the clarity of the stone.

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Laser drill hole: A tiny surface hole in a diamond, usually the result of drilling into the stone to remove an internal inclusion.

Lax diamond: A dull, fireless diamond.

Leaching: A technique for improving the appearance of some flawed diamond; hydrofluoric acid is used to reach inclusions open to the surface or from which fractures or cleavages radiate to the surface; thus unsightly flaws may be "leached" white.

Length-to-width ratio: A comparison of a diamond's length to its width, used to determine whether a diamond is relatively square or rectangular when viewed from the top.

Lobster claw clasp: A type of clasp that uses a tiny spring to keep the latch closed.

Loupe: The magnifying tool used to examine gemstones and jewelry. Typically to 10X magnification.

Loupe clean: A diamond that shows no flaws under magnification.

Luster: The appearance of a surface in reflected light. A diamond's luster gives it brilliance unobtainable in other stones. A diamond's luster is often referred to as adamantine luster.

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Make: The proportions of a diamond's cut. A certified diamond will have proportions that reflect light well to maximize brilliance.

Malleability: Property of precious metals of being extended or shaped by beating with a hammer, or by the pressure of rollers.

Mandrel: A steel rod slightly tapered, used by jewelers as an anvil for forming or sizing rings.  

Marquise-shape: A thin, elongated diamond with gently curved sides that come to a point on either end. Marquise is part of the brilliant cut family. This shape is used to maximize carat weight in the setting and give it a long, slender appearance.

Master stones: A set of diamonds by which jewelers can compare and grade the color of a particular stone from D to Z.

Micrometer: Measuring instrument in which the object to be gauged is brought up the end of a screw, which has a head graduated on its rim, from which the measurement is read. Calipers are made in inches, thousandths and ten-thousandths; and in metric measure in millimeters, tenths and hundredths.

Millimeter: Unit of length, or one thousandth of a meter. A millimeter is .03937 inch.

Mixed cut: This cut has both step cut and brilliant cut facets. Mixed cuts combine the beauty of the emerald cut with the sparkle of the brilliant cut.

Mohs hardness scale: A scale developed by Friedrich Mohs to quantify the hardness of minerals and gemstones. It utilizes a scratch test to rate diamonds on a scale of 1-10 (the higher the number, the harder the mineral will be).

Mold: A hollow form that gives shape to metal in its molten state.

Mountings: The method of holding gemstones in place in jewelry. Settings, prongs, channels, etc., are mountings.

MSRP: An abbreviation for "manufacturer's suggested retail price," a guideline provided by the manufacturer so that retailers may determine the value and set the retail price of items.

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National Stamping Act: U.S. Federal law, enacted in 1906, controlling quality marks on articles made in whole or part of gold or silver; 1961 amendment requires a registered trademark (the mark of a manufacturer, importer, wholesaler or retailer registered with the United States Patent Office) to accompany a quality mark.

Natural: A small edge of rough diamond that is left unpolished on the surface of the stone. Very minor naturals are not visible to the naked eye and do not affect the clarity of the stone or compromise its integrity.

Needle: A long, tiny crystal on the surface of a diamond. Very minor needles are not visible to the naked eye and do not affect the brilliance of the stone or compromise its integrity.

NGL: The Northwest Gemological Laboratories (NGL), an industry leader in diamond grading.

Nick: A small cut, notch, or indentation on the girdle or a facet edge.

Nickel (Ni): An elemental metal of important use in the jewelry trade. Pure nickel is white, hard, ductile and malleable. The principal use of nickel, when alloyed with gold, makes the latter harder, more ductile and paler; it replaces silver in white gold; it acts as a grain refiner, producing smooth surfaces after annealing or casting.

Niobium (Nb): A silvery, soft, ductile metallic element used in steel alloys.

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Off center culet: A major problem in gemstone cutting. An off center culet seriously affects the symmetry of a stone.

Off color: A color grading term for diamonds that display a more or less distinct tint of undesirable color, usually yellow, when viewed through the table by an experienced eye.

Oiling: A common procedure for gemstone color enhancement. The treatment is not permanent and should be disclosed at point of purchase.

Opaque: The term for a diamond that contains excessive inclusions and will not allow light to pass through the stone.

Osmium (Os): A hard, white metallic element of the platinum group; possibly the heaviest element known.

Oval shape: An even and perfectly symmetrical elliptical shape; basically, similar to Round, but elongated.

Oxidation: The forming of an oxide from base metals such as the copper in sterling silver or a karat gold alloy combining, through heat, with oxygen and forming a coating of copper oxide. Not to be confused with the discoloration of silver by sulphur and its compounds.

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Palladium (Pd): A white metallic element, used in dentistry, jewelry, and chemical and electrical equipment. Used to make white gold, without causing the stress corrosion that can happen in nickel alloys.

Pavé setting: Many small gemstones placed in tapered holes creating a "pavéd" appearance. Usually diamonds are set in white gold to create a sparkled finish.

Pavilion: The bottom part of a stone, under the girdle, measuring to the culet.

Pavilion depth: Along with crown height, pavilion depth determines the overall proportion and symmetry of a gemstone cut.

Pear shape: A hybrid cut, combining the best of the oval and the marquise, the shape is similar to a teardrop or pear.

Pearl: A smooth, lustrous, variously colored deposit, chiefly calcium carbonate, formed around a grain of sand or other foreign matter in the shells of certain mollusks and valued as a gem.

Pennyweight: A unit of Troy weight, used for weighing precious metals. The pennyweight contains one-twentieth of an ounce. Abbreviated "dwt."

Per carat cost: Total cost of a gemstone is equal to the carat weight X the per carat cost.

Pinpoint: Tiny, speck-like crystals inside a diamond. Several of these together may form a cloud in the stone that appears to be hazy.

Platinum (Pt): A white metallic element, popular in jewelry making. In it's pure form, it is soft and malleable. Hardness is noticeably affected by rolling and heat-treating, also by the presence of impurities, even in small amounts. Alloys containing 10% iridium or 5% ruthenium possess hardness and working qualities highly desirable in jewelry making, and are known as "hard platinum."

Plumb gold: A gold alloy of the same fineness as marked, or perhaps with a small tolerance such as .003. Not less than 14K gold.

Point: To easily quantify carats, jewelers assign 100 "points" to each carat and discuss weight based on portions of those points. A 50-point diamond, for instance, is the equivalent of a half-carat.

Polariscope: An instrument for studying the properties of, or examining substances in polarized light.

Polish: The smoothness of the facets of a diamond. Smoother facets reflect light more acutely and increase brilliance.

Poor cut: Cut refers to the angles and proportions a skilled craftsman creates in transforming a rough diamond into a finished diamond. A poorly cut diamond can be either cut too deep or too shallow. A deep or shallow cut diamond will lose or leak light through the side or bottom. This results in less brilliance and value.

Precious metals: Metals prized because of chemical and physical properties such as resistance to corrosion, hardness, strength and beauty. Common precious metals used for making jewelry are platinum, gold, silver and palladium.

Princess-cut: The Princess-cut is a very attractive square or sometimes rectangular cut, and it has some of the sparkle of a Round brilliant cut. Because of its design, this cut requires more weight to be directed toward the diamond's depth in order to maximize brilliance. It may have either 50 facets (21 crown, 4 girdle, 25 pavilion) or 58 facets (21 crown, 4 girdle, 33 pavilion), depending on how the pavilion is cut. Princess shapes of high cut quality usually have a table percentages between 60-75% and a total depth percentage between 65-80%.

Prong: One of several wires or claws on a setting used to fasten and hold a stone in place.

Prong or claw setting: Consists of four or six prongs that cradle the stone. Because this setting allows the maximum amount of light to enter a stone from all angles, it can sometimes make a diamond appear larger and more brilliant than its actual weight.

Proportion: The proportions of a diamond are very important, so that the maximum amount of light be reflected off and out of a stone. Proportion is the relationship between the angles of the facets of the crown and the pavilion.

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Quadrillion: A square cut diamond with 96 facets: 49 brilliant style, 21 crown and 24 pavilion. This differs from a Princess, which has either 50 facets (21 crown, 4 girdle, 25 pavilion) or 58 facets (21 crown, 4 girdle, 33 pavilion), depending on how the pavilion is cut.

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Radiant-cut: A 70 facet rectangular or square shaped diamond with step and scissor cuts on the crown, a brilliant cut on the pavilion and emerald cut corners.

Refining: Operations performed to extract metals in pure form from masses containing other metals or impurities.

Refraction: Refraction is when light enters a medium with a different optical density (like a gemstone), and the light is bent at an angle (and also changes its speed).

Rhodium (Rh): A white metallic element of the platinum group, commonly used as an electroplate finish on white gold to improve the white color.

Ring adjuster/Ring guard: A gold bridge with ears that clamp inside a ring that has to be oversized to go over an enlarged knuckle. Used to keep the ring from turning on the finger, or to decrease the size of a ring without cutting and re-soldering it.

Ring setting: The term for any ring prior to gemstone mounting.

Ring size: Proper ring size is based on the diameter of the wearer's finger and the size of her/his knuckle. The most common ring sizes range from 4 to 13. A size 4 ring has a circumferance equal to 46.5mm or 1-13/16 inches. There are many ways to determine a ring size. Click here to learn how.

Rough Girdle: A grainy or perforated girdle surface, often with nicks.

Round shape: A cut of diamond that is round and contains 57 facets. This is the most popular shape for engagement rings.

Ruthenium (Ru): A white metallic element of the platinum group, used mainly as a hardener for platinum or palladium. Melting point above 2400º C; specific gravity 12.2.

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Satin finish: A finish on jewelry given by dulling the polish by scratch brushing, sandblasting or chemical-treatment, producing a surface of metallic color, but with a soft, pearl-like luster instead of bright finish. Good to show off different colors of metals when jewelry uses multiple colors.

Saturation: The purity of a diamond's color, generally indicating an absence of brown or green hues in the stone.

Scintillation: Scintillation is the intense sparkling in a diamond as it moves. Black and white sparkles of scintillation show well in flood lit or office lighting environments where fire can be totally absent. Under pin point or spot lights, fire also adds to scintillation. Ideally a diamond has many pleasing flashes spread across the surface of the stone, with few dull dead patches.

Scrap: A class of jewelry-shop waste, cuttings of precious metals, large enough to sort for re-melting; differentiated from filings, sawdust and other small waste that has to be sweep-smelted and refined to recover it for use.

Semi-mount: A mounting that is set with only its small or sidestones but has not yet received its center or main stone

Semi-precious: The second and largest of the three categories into which gemstones have been divided by traditional usage. Stones such as topaz, garnet and amethyst are regarded as semi-precious, rather than precious, for relative softness, inferior brilliance, comparative abundance, unfamiliarity or fashion.  

Setting: The setting holds the stone in place. The combination of a shank and head make up a ring. Some popular settings are the Prong, Peg, Chanel, Bezel, and Pavé.

Shallow cut: Cut refers to the angles and proportions a skilled craftsman creates in transforming a rough diamond into a finished diamond. When a diamond is cut too shallow, it will lose or leak light through the side or bottom. This results in less brilliance and value.

Shank: The part of a ring that fits around the finger. The combination of a shank and head (or setting) make up a ring.

Shape: Refers to form or appearance of a diamond. Whether the diamond is round, triangular, square, marquise, pear, oval or heart shaped.

SI 1/SI 2 (Slightly Included): These two grades of slightly included diamonds contain inclusions that are evident under 10x magnification and may be seen by the naked eye in some cases (generally in SI2 diamonds). If your goal is maximizing size and/or affordability, look at S1 and S2 diamonds. Many of these stones are what professionals call "eye-clean," meaning they have no visible inclusions.

Side stone: A stone set as part of a group encircling a center stone.

Silver (Ag): A metallic element, used in jewelry, coinage, dentistry, photography, etc. It is the whitest of metals, harder than gold, softer than copper, more malleable and ductile than any metal except gold, and probably the best conductor of heat and electricity.

Single cut: A simple cut of 17 - 18 facets, given to small diamonds.

Soldering: Uniting pieces of metal by melting between them another kind of metal.

Solitaire: A single-diamond engagement ring.

Sparkle: The result of light entering a diamond and reflecting repeatedly throughout the stone. Also called brilliance or fire.

Specific gravity: A property of any substance, its weight in relation to an equal volume of distilled water at 4º C. It is one of the most important properties to aid in the determination of a gem.

Spectroscope: An instrument used in gem identification.

Step cut: The cut has rows of facets that resemble the steps of a staircase. The emerald cut and the baguette are examples of the step cut.

Symmetry: Symmetry refers to the angles at which the "facets" (the stone's smooth, angled surfaces) align. Proper symmetry reflects light from one surface to another repeatedly throughout the diamond (allowing as little light as possible to escape). Excellent symmetry of a well cut and well-proportioned diamond can have a great effect on the diamond's brilliance and fire. Grading reports will often state the diamond's symmetry in terms Excellent, Very Good, Good, Fair, or Poor.

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Table/Table facet: The largest facet on a gemstone. The table is on top of the crown and allows refracted light to escape, creating brilliance.

Table spread: The term used to describe the width of the table facet, often expressed as a percentage of the total width of the stone. The table should be between 53% and 67% of the girdle diameter.

Tempering: Increasing the hardness of metal by gradual heating to stages less than annealing heat.

Tension setting: A tension set diamond is held in place by the pressure of the shank's metal, which is designed to "squeeze" the stone.

Titanium (Ti): A silvery gray, light, strong metallic element found combined in ilmenite and rutile and used especially in alloys (as steel) and combined in refractory materials and in coatings.

Tone: A scale designed to measure color intensity in a diamond. Values range from "light" to "dark."

Total weight/Carat total weight: The total diamond carat weight of all the stones in a piece of jewelry.

Trademark: The mark of a manufacturer, importer, wholesaler or retailer registered with the United States Patent Office. Registration remains in force for 20 years; may be renewed for like periods.

Trillion shape: A triangular shaped diamond with 50 facets. Trillions are commonly used as side stones.

Troy ounce: A unit of Troy weight, long used for weighing precious metals. The ounce contains 20 pennyweights each of 24 grains.  

Twinning wisp: An irregularity in a diamond's crystal structure that appears as a line inside the stone. Minor wisps are not visible to the naked eye and do not affect the clarity of the stone or compromise its integrity.

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Ultrasonic cleaner: A cleansing agent dissolved in a solution and vibrated at frequencies higher than the those audible to the human ear. At such vibrations, foreign matter and dirt are dislodged while the jewelry is being cleaned.

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V-end: A prong setting designed to protect the fragile points of a diamond. The v-end shaped prong wraps around the point of fancy diamond shapes such as princess, emerald, marquise and pear.

Very Good cut: These diamonds reflect much of the light that enters the stone. They usually trade in some of their brilliance for added size.

Vickers hardness test: A test for metals in which a diamond pyramid is pressed into the metal by a load of 5-120 kilograms.

VS 1/VS 2 (Very Slightly Included): These two grades of Very Slightly Included Diamonds have minute inclusions that are not visible to the naked eye and are difficult to see under magnification. 10X magnification is required to clearly see an inclusion. VS clarity diamonds are a good choice for someone wishing to balance high quality with relative affordability.

VVS 1/VVS 2 (Very, Very Slightly Included): These two grades of VVS Diamonds have minute inclusions that are extremely difficult to detect even with 10x magnification. These diamonds are excellent choices as their inclusions are minor and invisible to the eye. These diamonds offer cost savings without sacrificing too much in terms of clarity.

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Wax injector: A device for forcing molten wax into a rubber or metal mold in order to make a wax pattern. Pressure for the wax injection is supplied by compressed air or hydraulic pressure.

Well cut: Well cut diamond proportions ensure the maximum compromise between fire and brilliance. When light enters a properly cut diamond, it is reflected from facet to facet, and then back up through the top, exhibiting maximum brilliance, fire and sparkle.

White diamond: A diamond color grade approximately equivalent to GIA grades F, G, H, and AGS grades 1 and 2.

White gold: An alloy of gold, with nickel or palladium.

Width: The horizontal size measurement of a piece of jewelry or gemstone.

The width of a ring or band is measured across the widest area, over the top of the ring as shown below. All measurements are approximate.

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Yellow diamond: A color-grading term measured by grade Z on the GIA scale or grade 10 on the AGS scale. Stones that are deeper than Z or 10 are designated fancy yellow.

Yellow gold: The most popular gold alloy. An alloy of gold, silver, copper and sometimes zinc.

Zinc: A bluish-white metal, melting point, 787º F; used in gold alloys to lower the melt temperature and improve malleability.

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