Gemstone Enhancement Definitions and 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.

On-Air Code: 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.

On-Air Code: LPLT

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.

On-Air Code: 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.

On-Air Code: 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.

On-Air Code: 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.

On-Air Code: 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.

On-Air Code: CVD

channel/pipe diffusion

The high temperature diffusion of coloring elements, such as copper, along certain channels in feldspar. Example: andesine-labradorite.

On-Air Code: 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.

On-Air Code: 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.

On-Air Code: POLY

filling

On occasion pits or blemishes on a pearl are filled with all manner of substances to repair imperfections and give a more uniform appearance.  As with all pearls please use gentle care and just wipe pearls with a soft clean cloth to remove body oils and dirt.  Avoid cosmetics, perfumes, hairsprays, heat, and household chemicals.

On-Air Code: FL

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.

On-Air Code: FH

fracture filled

The filling of surface-breaking cavities or fissures with highly refractive colorless glass. This process improves apparent clarity. Example: diamond

On-Air Code: FF

heated

The use of heat to alter color, clarity, and/or phenomena. Examples: ruby, sapphire, tanzanite, aquamarine, demantoid garnet.

On-Air Code: HE

HPHT

The use of high heat and pressure combined to affect desired alterations of color. Example: colored and near-colorless diamonds.

On-Air Code: 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.

On-Air Code: 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.

On-Air Code: 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.

On-Air Code: IRR

lasered

The use of a laser and chemicals to reach and alter inclusions. Example: diamond.

On-Air Code: 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.

On-Air Code: 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.

On-Air Code: LGF

normal care

In between professional cleanings, preserve your jewelry with "normal care" by cleaning it with room temperature water, mild soap, and a non-abrasive cloth. For thorough cleaning, visit a jewelry professional you trust who is familiar with the gemstones in your jewelry.

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.

On-Air Code: 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.

On-Air Code: 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.

On-Air Code: 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.

On-Air Code: 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.

On-Air Code: 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.

On-Air Code: 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.

On-Air Code: 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.

On-Air Code: 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.

On-Air Code: DIF

waxed

The impregnation of a colorless wax or paraffin in porous gemstones to improve their surface appearance. Examples: coral, amazonite.

On-Air Code: 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.

On-Air Code: ZPR

Common Gemstone Terms and Definitions

natural gemstones

A naturally occurring gemstone that has only undergone the standard process of cutting and polishing.

treated gemstones

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 gemstones

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 gemstones

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 gemstones

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 gemstones

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 gemstones

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.

gemstone 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 gemstones

Color has been improved by various processes or agents.

clarity enhanced gemstones

Clarity has been improved with colorless glass, oil, plastic, resin, or some similar substance.

gemstone hardness

Hardness is the ability to resist scratching.

gemstone toughness

Toughness is the ability to resist breakage (deformation in the presence of external forces).

gemstone stability

Stability is the ability to remain unchanged in the presence of heat, light, and/or chemicals.

gemstone durability

Durability is defined as a combination of hardness, toughness, and stability.

standard pearl processing

Routine cleaning and bleaching of cultured pearls.