gem, ornamental mineral or organic substance, Mineralogy And Crystallography

Related Category: Mineralogy And Crystallography

Precious and Semiprecious Gemstones

The precious stones are diamond; some forms of corundum (ruby, sapphire, Oriental emerald, Oriental topaz, and Oriental amethyst); and emerald. The chief semiprecious stones are aquamarine, amethyst, topaz, garnet, tourmaline, spinel, peridot (see olivine), zircon (see zirconium), chrysoberyl, quartz, opal, turquoise, moonstone, and jade. The organic gems are pearl, amber, coral, and jet; of these, pearl is usually counted as a precious stone.