Emeralds are again being mined in the historic district of the Ural Mountains. Physical, chemical, spectroscopic, and microscopic characteristics of stones from the recent production are presented and ...

Established in 1931, the Gemological Institute of America (GIA) is the world’s foremost authority on diamonds, colored stones, and pearls. A public benefit, nonprofit institute, GIA is the leading ...

莫氏硬度用以衡量宝石和矿物的硬度。 这些数值基于一种矿物可被其他物品划伤的相对难易程度得出。 但莫氏硬度会引起误导。 不同矿物的硬度等级之间的差距并不均匀。 举例来说，钻石的莫氏硬度只比刚玉高1度，但实际上它比刚玉家族的宝石坚硬好多倍。

Miners collect spinels from gravel at the end of a long day at Man Sin. Photo by Vincent Pardieu, © GIA. In the spring of 2001, I was studying gemology in Yangon ...

You need to sign a client agreement every time a new version is published. If a new signed client agreement is required, a Client Service Representative will reach ...

Consumers now, more than ever, have a heightened awareness of sustainably and ethically sourced products. The GIA Diamond Origin Report uses scientific evaluation to provide confirmation of a ...

Cultured pearls come in different sizes, shapes, and colors. Perhaps the best-loved gems of all time, pearls—both natural and modern cultured pearls—occur in a wide variety of colors. The most ...

As a consumer, you will regularly encounter in the marketplace gems that have been treated to change their appearance. A topic that often comes up is whether a particular gemstone is or isn’t treated.

The book examines the skeletons discovered by chance in Roman catacombs (underground tombs) in the mid-16th century. The Vatican declared the tens of thousands of skeletons found in these vast ...

This 15th-16th century icon of Mexican (Aztec) art, was probably worn on the chest on ceremonial occasions. ©The Trustees of the British Museum Turquoise is one of the world’s most ancient gems.

This sapphire from Kashmir has an intense velvety blue color. – Photo: Robert Weldon/GIA. Sapphire is one of the Big three of jewelry colored gemstones—the other two are ruby and emerald. A durable ...

刚玉（红宝石和蓝宝石）呈现出光谱中的各种颜色，从古至今一直是备受欢迎的宝石。摄影：Robert Weldon（罗伯特·韦尔登）/GIA 几千年来，红宝石和蓝宝石（通常为蓝色，有时也有各种其他颜色）一直都是最重要的有色宝石。这些刚玉族矿物包含各种颜色类别 ...