Tourmalines have a very complex chemical composition, and more than a dozen mineral species are recognized within this group.

Among the collection assembled by Dr. Edward Gübelin are a number of uncommon gemstones from many worldwide localities.

Among the collection assembled by Dr. Edward Gübelin are a number of uncommon gemstones from many worldwide localities.

化学上纯净的绿柱石是无色的，但是微量元素使它呈现出绿色，蓝色和粉红色/红色。

Although colorless when chemically pure, zircon is typically yellow-brown to brown. It also comes in red, blue, purple, and green. Because of its high brilliance and dispersion, colorless zircon has sometimes been used as a substitute for diamond in jewelry.

Among the collection assembled by Dr. Edward Gübelin are a number of uncommon gemstones from many worldwide localities.

The range of Tanzanian gems’ lovely colors — both natural and slightly treated — is Mr. Sevdermish’s particular passion.

This document provides guidelines for submitting manuscripts for publication to the Gems & Gemology journal.

Among the collection assembled by Dr. Edward Gübelin are a number of uncommon gemstones from many worldwide localities.

Among the collection assembled by Dr. Edward Gübelin are a number of uncommon gemstones from many worldwide localities.

Found in nearly every color – most notably red, pink and blue – spinels are popular gemstones because of their abundance, moderate cost and attractiveness.

Often thought of as a deep red gemstone, garnet can also be yellow, orange, green or brown – any color except blue.