Ammolite is a form of aragonite that is obtained from vivid iridescent fossilized ammonite shells mined in Alberta, Canada.

Gemstone enhancements and their disclosure became the most important gemological issue for the jewelry trade in the 1990s.

The 1990s saw growth in gem exploration, production, and marketing worldwide.

Haüyne is a rare mineral and an extremely rare gemstone.

Two archeological sites that were discovered recently on the island of Antigua appear to have had flourishing lapidary industries.

Since 1996, large quantities of yellow to blue sapphires have been recovered from alluvial deposits derived from basaltic rocks in northern Madagascar.

An investigation of these Yuruty mine samples revealed an interesting new aspect to this bicolored quartz.

Greenish yellow to yellowish green HPHT-treated diamonds exhibited highly saturated body color, well-defined brown to yellow octahedral graining, and visual evidence of heating, among other characteristics.

This study provides detailed mining and gemological information on the Jegdalek deposit, in east-central Afghanistan, which is hosted by elongate beds of corundum-bearing marble.

There has been considerable debate in the gem trade concerning the nucleation procedures being used to grow large round Chinese freshwater cultured pearls.

Results from spectroscopic analyses of GE POL high-pressure high-temperature (HPHT) annealed nominally type IIa diamonds are presented, and these spectral characteristics are compared with those of untreated diamonds of similar appearance and type.

A compilation of gem news from around the world, covering topics such as localities, unusual gem materials, market news, new products, discoveries, jewelry manufacturing techniques, and industry trends.

Lapis lazuli has been mined from the Coquimbo Region of Chile since 1905.

The jadeite mines of Upper Burma (now Myanmar) occupy a privileged place in the world of gems, as they are the principal source of top-grade material.

Gemological, chemical, spectroscopic, and microscopic properties of blue-green color-change garnets from a new deposit near Bekily, Madagascar, are given.

Gem-quality synthetic ametrine has been produced commercially in Russia since 1994.

Criteria for distinguishing emerald filling substances were investigated.

Greater amounts of colorless sapphire—promoted primarily as diamond substitutes, but also as natural gemstones—have been seen in the gem market during the past decade.

Over the last 10 years, millions of carats of turquoise have been enhanced by a proprietary process called the Zachery treatment.

More than 400 blue diamonds were studied at the GIA Gem Trade Laboratory over several years to reveal additional information about the relationships between their color, clarity, and other gemological properties.