Gemstone simulant

A gemstone simulant is a material used to resemble another gem while having a different chemical composition, structure and physical properties. A simulant may be natural or manmade.

Common materials

Glass has long imitated gems in many colours. Cubic zirconia, usually called CZ, is a common diamond simulant. A synthetic gem is manmade but has essentially the same chemical and crystal properties as its natural counterpart. It is therefore not the same category as a simulant.

Assessment

Appearance alone is not conclusive. Bubbles, wear and moulded facet edges may suggest glass, but secure identification requires gemmological testing. Describe the material as unknown or imitation when evidence is insufficient.

Source: Gemological Institute of America, Simulants or imitation gem materials.