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.