All other quality stones are called semiprecious even though they may not be any less valuable or beautiful. Flint is a hard rock mostly gray or black in color and with a waxy or glassy appearance. The traditional list of gemstones that are considered precious stones are. In antiquity topaz zircon and moonstone were also in the precious stones list as were opaque gemstones like turquoise carnelian agate onyx sardonyx jasper and bloodstone. The ancient greeks made a distinction between precious and semiprecious gems which is still used.
The brown and green gems from tanzania are enstatites as are the brownish green stones from sri lanka. The only precious gemstones are diamond ruby sapphire and emerald. Green and brown gems from india and brazil tend to be in the bronzite composition range. These days all gemstones are considered precious since they are all rare and there is a limited supply of them. Precious stones were hard rare and valuable.
These terms are based on old traditions from the west. Indeed tourmaline alexandrite and garnet were among the names of precious stones and rightly so since these gemstones can even be more expensive than emerald or sapphires. These terms are based on old traditions from the west. The brown and green gems from tanzania are enstatites as are the brownish green stones from sri lanka. All other quality stones are called semiprecious even though they may not be any less valuable or beautiful.
