Gemstone Terms

Gemstone Terms
Natural A naturally occurring 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.