Gemstone Enhancement Definitions and Gemstone Terms

Gemstone Definitions with On-Air Codes

assembled The assembling of natural with natural and/or man-made parts to improve durability or appearance. Examples: opal doublet, mabe pearl, quartz triplet. AS
autoclave treated A method of applying moderately low heat and pressure. Commonly done with copal to create green amber. This treatment simulates a rapid aging process, making the stability of copal comparable to amber while also creating a green color. LPLT
B-Jade Natural jadeite that has been acid bleached to remove stains and impurities and is then filled with a polymer, usually with color added, to improve translucency and color. B-Jade
blackened The process of darkening the bottom of a piece of amber to alter the color. Blackening the bottom of golden amber creates a greenish color. BLKND
bleached The use of heat, light, and/or chemicals or other agents to lighten or remove a gemstone's color. This is sometimes accompanied by subsequent dying and/or impregnating to stabilize the resulting color. Examples: cultured pearl, golden coral, B-jade. BL
coated The use of such surface enhancements as lacquering, enameling, inking, foiling, or sputtering of films to improve appearance, improve durability,provide color or add other special effects. Examples: some pearls, black star sapphires, some topaz, many beads. CTD
composite Composed of disparate pieces of various gem materials that are bonded together. May be dyed or bonding agent may impart color. Components may all be one type of gem material or mixed varieties. Examples: polycoral, mosaic turquoise, rainbow calsilica. COMP
CVD "Chemical Vapor Deposition" - A high-tech coating process that is commonly applied to the pavilion (bottom) of stones to change or improve their color. Examples: diamond, mystic topaz. CVD
channel/pipe diffusion The high temperature diffusion of coloring elements, such as copper, along certain channels in feldspar. Example: andesine-labradorite. DIF
dyed/stained The introduction of coloring matter into a gemstone to give it new color, intensify existing color or improve color uniformity. Examples: dyed green jadeite, lapis. DYED
Excel/infused with hardened polymers The filling of surface-reaching fissures with colorless polymers to improve clarity. Includes the proprietary Excel™ treatment as well as other semi-permanent processes which allow for ease of care and normal cleaning without degrading the appearance of the stone. The latest generation of treatment technology, these processes bring out the natural beauty of the emerald while minimizing care concerns. POLY
flux healed During heat enhancement, fluxes may be used to heal natural fissures. The process leaves glass residues, but minor when compared to infilling or lead glass treatments. Example: ruby. FH
fracture filled The filling of surface-breaking cavities or fissures with highly refractive colorless glass. This process improves apparent clarity. Example: diamond FF
heated The use of heat to alter color, clarity, and/or phenomena. Examples: ruby, sapphire, tanzanite, aquamarine, demantoid garnet. HE
HPHT The use of high heat and pressure combined to affect desired alterations of color. Example: colored and near-colorless diamonds. HPHT
impregnated The impregnation of a porous gemstone with a colorless agent (usually plastic) to give it greater durability and improve appearance. Examples: stabilized turquoise, coral. IMP
infilling The filling of surface-breaking cavities or fissures with colorless glass or fluxes during the heat treatment process. Improves clarity and color, and it may possibly add weight. Lead is not present in these materials. Example: ruby. INF
irradiated The use of neutron, gamma, ultraviolet and/or electron bombardment to alter a gemstone's color. The irradiation may be followed by a heating/annealing process. Examples: blue topaz, colored diamonds. IRR
lasered The use of a laser and chemicals to reach and alter inclusions. Example: diamond. LAS
lattice diffusion The heat treatment at high temperatures with beryllium that deeply penetrates the gem material to alter the color. Examples: some padparadscha or yellow sapphires. BE DIF
lead glass filling (hybrid) A similar process to "infilling" using lead glass. Performed at lower temperatures, this is a less durable treatment and should be treated gently. Improves clarity, color, and may add weight through the filling of voids and fissures. In sapphires, cobalt is usually added to improve color. Requires Special Care.Examples: plum star ruby, Mahaleo ruby, cobalt-lead sapphire. LGF
oiled/resin infused The filling of surface-breaking fissures with a colorless oil, wax, resin, or other colorless substance except glass or plastic, to improve the gemstone's clarity. Example: emerald and any stone with surface reaching fissures. O
pressed The process of partially melting and pressing together smaller pieces or powders of natural resins such as amber and copal. Pressed amber retains the same properties of unpressed amber. In addition, it usually improves clarity and may have color added. PRS
PVD coated Physical Vapor Deposition Coated - A coating that is commonly applied to the surface of the product; which is then sealed with a polymer to protect it. Example: watches. PVD
quench-crackled A process mainly applied to quartz. By placing super-cooled stones into a very hot fluid, can add color while inducing a pattern of cracks. Example: green quench-crackled quartz to imitate emerald. QCR
reconstructed (see composite) Small particles of natural material compressed and bonded into a larger whole. Also referred to as reconstituted, but better classified as composite. Example: some turquoise. RECON
smoke In the smoke treatment process, smoke penetrates the opal to darken the background color. This process results in a better contrast and brings out the play of color. Example: Ethiopian Chalama opal. SM
stabilized Not to be confused with reconstituted turquoise, the more valuable stabilized turquoise is solid, whole turquoise that has been filled with colorless polymer to reduce porosity, providing a polished finish that protects the stone against breakage and discoloration. The color always improves as a result of the treatment, but some processes may add additional dyes as well. When color is added, this is additionally disclosed. STB
sugar acid In the sugar treatment process, the matrix opals are heated in a saturated sugar solution. The matrix material absorbs this sugar. It is then immersed in concentrated sulfuric acid. A chemical reaction takes place between the sugar and acid, leaving only the remaining carbon. This carbon darkens the background color of the gems which enhances the play-of-color and makes the stone appear brighter. SA
surface diffusion The outside-in diffusion of elements via high-temperature heat treatment to produce a layer of color and/or asterism. Examples: some blue sapphire, some star sapphire. DIF
waxed The impregnation of a colorless wax or paraffin in porous gemstones to improve their surface appearance. Examples: coral, amazonite. W=WAXED
Zachary process Zachary processed turquoise has been treated with chemicals, and then heated. The process does not alter the properties of the turquoise, but does improve color and stability. ZPR

Gemstone Terms

natural A naturally occuring gemstone that has only undergone the standard process of cutting and polishing.
treated Gemstones that have undergone changes in color, clarity, and/or durability. Processes described as treatments typically go beyond what is considered standard enhancement. Examples: diffused sapphire, Mystic topaz (CVD), irradiated blue diamond
artificial/man made The term artificial is a catch-all for any man made or lab-created gem. Artificial gems that have the same chemical, optical, and physical properties as their natural counterparts are more accurately described as synthetic. Any gemstone not of natural origin is considered artificial in gemological terms.
synthetic The term synthetic is used to describe a lab-created gemstone that has a natural counterpart. Synthetic gemstones have the same chemical, optical, and physical properties as those occurring in nature. Examples: synthetic sapphire, synthetic alexandrite
simulant The term simulant is synonymous with substitute or imitation. A simulant only mimics the appearance of another more expensive gemstone. A simulant usually indicates a man-made material, but may be natural. Examples: red glass (ruby simulant), white YAG (diamond simulant), sodalite (lapis substitute)
lab created The term lab created is used to describe any material made by man. Lab-created gems with no natural counterparts fall into the category of artificial, and are used as simulants. Lab-created gems that duplicate the same chemical, optical, and physical properties as their natural counterparts are more accurately described as synthetic.
imitation See simulant. The term imitation is used to describe any material that mimics the appearance of a natural or more expensive gemstone. Imitations may be man-made or natural. Examples: red glass (imitation ruby), white YAG (imitation diamond), red garnet (imitation ruby)
hybrid A stone with natural and artificial components, where the two cannot be separated. New category created by a new generation of treatments that add materials to a natural base material. In most cases, undesirable elements of a natural material are removed and replaced by added artificial gem material; lead glass, polymers or synthetic material. Some require special care.
enhancement A process that improves a natural gemstone's appearance or durability by an accepted industry practice. Examples: heated citrine, bleached Akoya pearls
color enhanced Color has been improved by various processes or agents.
clarity enhanced Clarity has been improved with colorless glass, oil, plastic, resin or some similar substance.
hardness Hardness is the ability to resist scratching.
toughness Toughness is the ability to resist breakage (deformation in the presence of external forces).
stability Stability is the ability to remain unchanged in the presence of heat, light, and/or chemicals.
durability Durability is defined as a combination of hardness, toughness, and stability.
standard pearl processing Routine cleaning and bleaching of cultured pearls.