Oriental Amethyst — An Obsolete Trade Name for Purple Sapphire
Oriental Amethyst — An Obsolete Trade Name for Purple Sapphire
A nineteenth-century misnomer for corundum, discouraged under modern disclosure
Oriental amethyst is an obsolete trade term for purple or violet sapphire — corundum coloured by chromium and iron — used historically to distinguish gem-quality corundum from quartz amethyst and to imply Eastern provenance. The term is a misnomer in the technical sense: amethyst by definition is the purple variety of quartz, and corundum and quartz are different species with different chemistry, hardness, and optical character. Modern disclosure standards, including those endorsed by the Gemological Institute of America and the American Gem Trade Association, require that the species name sapphire be used, with a colour modifier where helpful. The compound term oriental amethyst should be avoided in trade use.
Origin of the term
The qualifier oriental entered nineteenth-century gem terminology to denote stones thought to be of superior quality or of Asian origin, often coupled with a familiar western variety name to communicate colour. Oriental amethyst for purple sapphire, oriental emerald for green sapphire, oriental topaz for yellow sapphire, and oriental aquamarine for blue-green sapphire all follow the same pattern. The vocabulary served a market that valued the optical superiority of corundum over the species the term superficially named, but it conveyed no useful information about the actual species and obscured the simpler fact that the stone was sapphire.
Why the term is discouraged
The technical objection is that the term combines a qualifier (oriental) with a species name (amethyst) that does not apply. A purple sapphire is not amethyst by any chemical, structural, or optical criterion. The species is corundum (Al2O3), hardness 9, refractive index 1.760 to 1.778, with birefringence of 0.008 and a uniaxial-negative optic character. Amethyst is quartz (SiO2), hardness 7, refractive index 1.544 to 1.553, uniaxial-positive. Calling the corundum stone an amethyst, even with a qualifier, misrepresents the species and the durability of the material to a buyer who reasonably relies on species identification.
Both the GIA and AGTA disclosure standards, as well as the laboratory practice of every reputable coloured-stone laboratory, identify purple corundum as purple sapphire or violet sapphire. Use of oriental amethyst in selling material to a consumer is a disclosure problem and would be a contract problem in any market with active enforcement of trade-description standards.
Practical guidance
If a stone is offered as oriental amethyst, the buyer should ask for the species identification. If the stone is corundum, it should be sold as purple or violet sapphire and may be accompanied by a laboratory report stating species and treatment. If the stone is quartz amethyst, it should be sold as such and not under a compound term suggesting otherwise. Older auction catalogues and antique-jewellery descriptions sometimes reproduce the historical term for reference; in such cases, the species identification of the stone in question should be verified by gemmological examination rather than read off the catalogue label.
See also sapphire, oriental emerald, oriental topaz, oriental aquamarine, amethyst.