Figure 1. Diamonds such as this 1.15 ct round brilliant are some of the most highly sought-after gem materials and may contain inclusions that give the gemologist clues about their origin or treatment ...

GIA laboratory-grown diamond services include an overall quality assessment for laboratory-grown diamonds. The GIA assessments for laboratory-grown diamonds have a distinct format to fully ...

The history of Baja California has been closely tied to the exploitation of pearls since the 16th century. Using rudimentary diving techniques for most of this era, European and Mexican entrepreneurs ...

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Figure 1. The GIA 7 Pearl Value Factors system classifies pearls according to size, shape, color, luster, surface, nacre, and matching. Composite photo by GIA staff. Prized by many cultures throughout ...

Since its introduction in the early 1950s, GIA’s D-to-Z scale has been used to color grade the overwhelming majority of colorless to light yellow gem-quality polished diamonds on which laboratory ...

Vivid blue, green, and purple-to-violet cuprian elbaites, renowned in the gem trade as “Paraíba” tourmalines, continue to be recovered in small amounts from northeastern Brazil. Since the initial ...

Since late 2007, rubies and sapphires have been mined by hand methods from both eluvial and primary deposits at Winza in central Tanzania. The gem corundum is related to “dikes” of amphibolitic rocks ...

Only during the last few years have the gem riches of Pakistan become known to the rest of the world. This article reports on three gem materials currently being mined: emerald, corundum (most ...

There is only one known commercial occurrence of gem-quality red beryl in the world: the Ruby Violet (or Red Beryl) mine in the Wah Wah Mountains of Beaver County, Utah. The beryl is found mostly ...

这款 3.74 克拉 公主方形切工中等色调蓝色海蓝宝石由22 颗钻石环绕其周围。 这枚戒指是 Zoltan David（大卫·佐尔坦）的原创设计，已获得版权保护。 — Robert Weldon（罗伯特·韦尔登），由 Nancy's ...