Well polished precious stones display a decided lustre, which assists in determining their species. The following is a list of some precious stones and their lustre:

Adamantine.—Diamond, zircon.

Resinous.—Garnet.

Vitreous.—Emerald, ruby, spinel.

Waxy.—Turquois.

Pearly.—Moonstone, opal.

Silky.—Crocidolite, quartz cat’s-eye.

Metallic.—Hematite.

Greasy.—Olivine.

Some stones vary in lustre, from vitreous to pearly, etc.