For more than 100 years, Africa has produced large commercial quantities of diamonds and important individual stones.

The emeralds of the Ural Mountains, in what is now called the Russian Federation, have been known for more than 160 years.

This article illustrates the various features in filled diamonds and explores the best techniques for examining them.

A history of pearls in jewelry and fashions through the ages.

Yogo Gulch, discovered more than 100 years ago, is one of four major sapphire-producing areas in Montana, United States.

Primary occurrences of ruby, pink sapphire, sapphires of other colors, and spinel have been found in marbles in the Ural Mountains.

Many deposits of gem corundum are associated with alkali basalt.

Inclusions of native copper and tenorite (CuO) were found in grayish green elbaite from São José da Batalha, Paraíba, Brazil.

Analysis of a transparent yellow angular crystal inclusion in a Brazilian rock crystal quartz host suggests monazite.

Renewed interest in large-scale commercial mining of Montana sapphires motivated a detailed study of the heat treatment of sapphire from the Rock Creek deposit.

Sri Lanka is world famous for its gem wealth, but the actual extent of the deposits has never been determined.

Strongly etched prismatic crystals of yellow, green, and pale blue gem beryl have been quarried from a pegmatite dike in Luumäki, Finland.

Blue diffusion-treated sapphires have become a subject of considerable controversy since their introduction in significant quantities a few years ago.

After almost 75 years of inactivity, the deposits of boulder opal in Queensland, Australia, began to attract new interest in the 1960s and 1970s.

Verifying the gold content of karat-gold jewelry is a problem for the entire industry.

Diamond production’s future appears to belong less to Africa and more to Australia, Canada, and the Russian Federation, according to this overview of geologic trends in the industry.

The "bleaching" treatment of jadeite jade has become prevalent in higher- as well as lower-quality material.

Burma, now named Myanmar, has for centuries been considered the world's preeminent source of fine rubies.

The East African nation of Tanzania has great gem wealth.

The stony-iron meteorites known as pallasites are famed for the areas of yellowish green olivines they contain.