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.

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.

Verifying the gold content of karat-gold jewelry is a problem for the entire 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 gemological properties of a new ruby imitation, produced by dyeing natural colorless to pale-colored corundum, are described.

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.

A series of cuts, designed by the author, exhibit extraordinary optical effects that result from a combination of curved surfaces and plane facets placed to take advantage of internal reflection.

The Ponderosa mine is now producing commercial quantities of the gem-quality labradorite feldspar known as sunstone.

Gem-quality rubies and pink to purple sapphires are being recovered from the Luc Yen and Quy Chau mining regions of Vietnam.

This section, from the Spring 1991 issue of Gems & Gemology, is a compilation of interesting finds from GIA’s laboratories.

Although certain concepts about the age and formation of diamonds have been known for some time, this overview of advances over the decade leading up to the early 1990s have expanded the scientific understanding of this fascinating topic exponentially.

This article reports on the gemological properties of six large black diamonds set in a suite of jewelry.

Today, only by combining different gemological tests with years of practical experience, can a conclusive determination of the origin of a sapphire be made.

In addition to its rich history, the Dresden Green offers an opportunity to gain information about how to distinguish natural from laboratory-irradiated green diamonds.

Physical, chemical, spectroscopic, and microscopic characteristics of a sample of hydrothermally grown synthetic aquamarine from the USSR are presented.

Unusually vivid tourmalines from the state of Paraiba, in north eastern Brazil, have attracted great interest since they first appeared on the international gem market in 1989.

This article discusses the history of the Majorica imitation pearl, the manufacturing and marketing processes, and the separation of the Majorica product from its cultured counterparts.