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 ...

Each year basalt-topped Peridot Mesa, on the San Carlos Apache Reservation, is a major source for thousands of carats of gem-quality peridot in sizes suitable for use in modern jewelry. Marketed ...

Diamond “type” is a concept that is frequently mentioned in the gemological literature, but its relevance to the practicing gemologist is rarely discussed. Diamonds are broadly divided into two types ...

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.

Figure 1. Pleochroism in a 15 ct tanzanite, as seen with the unaided eye through the crown and the pavilion sides and ends. Photo by Wimon Manorotkul. In describing colored gemstones, the major ...

Observations of Oval-, Pear-, and Marquise-Shaped Diamonds: Implications for Fancy Cut Grading Presents findings from observations of oval-, pear-, and marquise-shaped diamonds, laying the groundwork ...

「GIAの社長兼CEOであるスーザン・ジャックは、6月2日（金）にJCKラスベガスショーで発表された、初のGIA（米国宝石学会）サステナビリティレポートについて、「私たちが事業を行う環境、社会、地域社会に与える影響を理解することは、私たちが掲げる ...

如今，市场上的大多数消费者选择圆形明亮式切工钻石，都是为了迎合现代人的审美观念。 这些闪闪发光的宝石凝聚着六个多世纪以来，一代又一代技艺高超的切工人才的集体智慧。 由于钻石切工逐渐演变成现在的 57 或 58 个刻面圆形明亮式，其风格也经过了 ...

GIA studied more than 400 important gemstones from the Gübelin Collection and is committed to sharing this repository of gemological information. This work is a valuable resource for all students, ...

Most colored gemstones form near the earth’s surface in a wide range of different environments; for example, they can crystallize from igneous magmas or hydrothermal solutions, or via the ...

这颗大型澳大利亚淡色凸圆面蛋白石，重达 117.85 克拉。蛋白石上面布满了橙色和绿色的星火图案小型游彩闪光，灰色的体色缀以柔和的蓝色斑点。 每一颗蛋白石的外观和质量都大有不同。正如雪花和指纹一样，每颗宝石都有明显的差异。 蛋白石评估应在可控 ...

Zircon comes in a wide variety of colors. Colorless zircon is well known for its brilliance and flashes of multicolored light, called fire. These two zircon properties are close enough to the ...