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 ...

The 75.47-carat Hooker Emerald was worn by Ottoman Sultan Abdul Hamid II, the last sultan of the Ottoman Empire. Photo by Chip Clark, courtesy Smithsonian Institution, National Museum of Natural ...

Fine-color, large, and eye-clean (lacking visible inclusions) rubies like this 11.01carat (ct) stone from Myanmar (formerly known as Burma) are extremely rare and valuable. – Photo: Robert Weldon/GIA.

To address concerns about laboratory-grown and treated diamonds being mixed into parcels of melee, GIA has developed an automated system to analyze and sort melee-size diamonds quickly and accurately.

Opal can range from 5 to 6.5 on the Mohs hardness scale. Hardness and toughness Gem and mineral hardness is measured on the Mohs scale. The numbers are based on the relative ease or difficulty with ...

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 ...

Everywhere on earth, people honor and appreciate the beauty and mystery of gems. And so it follows that everywhere you go, you also find the gem and jewelry industry. Just like the gems that are at ...

Diamond is available in a range of sizes and qualities to fit every consumer's tastes. One of the first things most people learn about diamonds is that not all diamonds are created equal. In fact, ...

标记每个晶体边缘的切口被称为重入角。 有色宝石专家根据宝石所显示的颜色变化程度以及它们在不同的光线条件下所显示的红色和绿色色彩品质，来评定优良亚历山大变石。 寻找珠宝商 使用邮政编码寻找您附近有 GIA 报告和有 GIA 训练有素的工作人员的珠宝商 。

GIA instructors are passionate educators who bring years of industry experience to the classroom. All are leaders in their fields, and all are dedicated to helping you gain knowledge, acquire skills ...

GIA evaluates ruby but does not grade it. A GIA Colored Stone Identification & Origin Report assesses the characteristics of a ruby (weight, measurements, shape, cutting style and color), indicates ...

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 ...