Glossary: Colored Gems
The cloudy bluish white light in a moonstone, caused by scattering of light.
Lacking a regular crystal structure.
Crossing of chatoyant bands, creating a star in the dome of a cabochon.
A glittery effect caused by light reflecting from small, flat inclusions within a gemstone.
Characteristic or irregularity confined to the surface of a polished gemstone.
A gemstone's basic color, determined by its selective absorption of light.
Cutting style with triangular or kite-shaped facets that radiate from the center toward the girdle.
A smoothly rounded polished gem with a domed top and a flat or curved base.
Gemstone sizes cut to fit standard mountings.
A gem carving style in which the design, often a woman's profile, projects slightly from a flat or curved surface.
Treatment that fills and seals voids to improve appearance and add weight.
Bands of light in certain gems, caused by reflection of light from many parallel, needle-like inclusions or hollow tubes.
A gemstone's relative freedom from inclusions and blemishes.
Internal or external feature of a gemstone that helps determine its quality.
A smooth, flat break in a gemstone parallel to planes of atomic weakness.
A small defect in the atomic structure of a material that can absorb light and give rise to a color.
A distinct change in gem color under different types of lighting.
The selection of colors in which a gemstone occurs.
Areas of different color in a gem, caused by variations in growth conditions.
Any gem material other than diamond.
Filling of pores or other openings with melted wax, resin, polymer, or plastic to improve appearance and stability.
Market sector where average-quality gemstones are used in mass-market jewelry.
A curved and ridged fracture in a gemstone, extending from the surface inward.
The network of tiny fractures that develops when an opal loses moisture.
Regular, repeating internal arrangement of atoms in a material.
A city, region, or country with a large number of gemstone manufacturers.
The weight of an object in relation to its size.
Artistic gem cuts that aren't limited to specific proportions or shapes.
The separation of white light into spectral colors.
Two separate pieces of material fused or cemented together to form a single assembled stone.
A gemstone's ability to withstand wear, heat, and chemicals.
A treatment that adds color or affects color by deepening it, making it more even, or changing it.
Dark areas in a faceted transparent colored stone.
Description for a gem with inclusions visible only under magnification.
A flat, polished surface on a finished gem.
Any gemstone shape other than round.
A free-form cut that can feature alternating curved and flat surfaces.
Inexpensive, or "costume," jewelry, often composed of materials other than precious metals and gemstones.
Another term for gem cutting and polishing.
A general term for a break in a stone.
A characteristic or part of a piece of jewelry.
Federal Trade Commission (FTC)
A US Government agency that issues guidelines for the jewelry trade.
Small components used to make or repair jewelry.
The color or colors in a gemstone's color range considered by the trade to be the most desirable.
The quality of the polish and precision of the cut of a fashioned gemstone.
A process in which powdered chemicals are dropped through a high-temperature flame onto a rotating pedestal to produce a synthetic crystal.
Small pocket in a gem that's filled with fluids and, sometimes, gas bubbles and tiny crystals.
Emission of visible light by a material when it's stimulated by ultraviolet radiation.
A process in which nutrients dissolve in heated chemicals, then cool to form synthetic crystals.
Any break in a gem other than cleavage or parting.
Fracture (Fissure) Filling
Using a filler to conceal fractures and improve the apparent clarity of a gem.
A broad gem category based on chemical composition and crystal structure.
A subcategory of species, based on color, transparency, or phenomenon.
A family of gems from several closely related mineral species.
Any jewelry store that specializes in high-end goods.
How well a gemstone resists scratches and abrasion.
Exposing a gem to rising temperatures for the purpose of changing its appearance.
The first impression of an object's basic color.
A process in which nutrients dissolve in a water solution at high temperature and pressure, then cool to form synthetic crystals.
A mineral crystal trapped within a gem as it grows.
A characteristic enclosed within a gemstone or reaching its surface from the interior.
Composed of, or arising from, non-living matter.
A design engraved into the surface of a gemstone.
A rainbow effect created when light is broken up into spectral hues by thin layers.
Exposing a gem to radiation to change or improve its color.
A broad flash of color in labradorite feldspar that disappears when the gem is moved.
Exposing a gem to high temperatures and chemicals to allow penetration of color-causing elements.
The appearance of a material's surface in reflected light.
The international unit of measurement for gem weight (1 carat equals 0.20 gram).
Milk & Honey
A two-toned effect seen when a chatoyant gem is positioned at right angles to a light source.
A cutting style that combines brilliant-cut and step-cut facets.
Gems produced by natural processes, without human help.
Iridescence seen in some natural and cultured pearls and mother-of-pearl.
A rare pinkish orange sapphire.
A flat break in a gemstone parallel to a twinning plane.
The price of a gem divided by its carat weight.
An unusual optical effect displayed by a gem.
The flashing rainbow colors in opal.
When a gem shows different bodycolors from different directions.
One one-hundredth of a carat (0.01 ct.).
The angles and relative measurements of a polished gem, and the relationships between them.
A historical record of ownership or origin for a gem or piece of jewelry.
A process in which the synthetic crystal grows from a seed that is dipped into a chemical melt, then pulled away as it gathers material.
A rapid heating and cooling process that produces fractures in a stone so it will accept dye.
A color's strength or intensity.
Flashes of light displayed by a polished gemstone when the gem, the observer, or the light source moves.
Process by which a material absorbs some components of visible light and returns others.
The part of a ring that encircles the finger.
The face-up outline of a gem.
Group of fine, needle-like inclusions.
Heating a wrapped opal until smoke or ash penetrates its surface to darken it and bring out its play-of-color.
A gem-producing area, or a particular mine in that area.
Ratio of the weight of a material to the weight of an equal volume of water.
How well a gemstone resists the effects of light, heat, and chemicals.
A machine that cleans jewelry with high-pressure steam.
Cutting style with mainly square and rectangular facets arranged in concentric rows.
Soaking an opal in a hot sugar solution and then in sulfuric acid to darken it and bring out its play-of-color.
Altering a gem's appearance by applying backings, coatings, or coloring agents like paint.
A laboratory creation with essentially the same chemical composition, crystal structure, and properties as its natural counterpart.
Restatement of a benefit, posed as a question and designed to elicit agreement.
A two-part sales technique that removes a customer's "just looking" defense.
A procedure for receiving customer jewelry for repair, appraisal, or cleaning.
Damage caused by sudden, extreme temperature changes.
Degree of darkness or lightness of a color.
Total Gem Weight
The combined weight of all the stones in a piece of jewelry that contains a variety of gems.
How well a gemstone resists breaking, chipping, and cracking.
Atoms in a gem that aren't part of its essential chemical composition.
Terms often used in the jewelry industry to describe particular gemstone colors or link gems with specific geographic locations.
Degree to which a material allows light to pass through it.
Any human-controlled process, beyond cutting and polishing, that improves the appearance, durability, or value of a gem.
The part of the add-on close that requires the customer to make a "yes" or "no" decision.
A single assembled stone made from three separate pieces of material fused or cemented together, or from two pieces and a colored cement layer.
Location of a change of direction in a gemstone's crystal structure during growth.
A machine that cleans jewelry with high-frequency sound waves in a liquid solution.
An area of weak saturation in a transparent gemstone's bodycolor that usually results from the way the gem was cut.