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.

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 green turquoise cabochon, from an American mine, might become part of a designer’s unique jewelry piece. The even blue color of the cabochon on the right would be called “Persian blue” in the ...

This 5.30-carat emerald from Brazil has a slightly bluish green color. Courtesy John Parrish, courtesy African, Brazilian, Colombian Gems Incorporated. Emerald has many special qualities, but colored ...

The majority of saltwater and freshwater pearls bought and sold in the global jewelry markets are “whole pearls,” sometimes referred to as “cyst pearls” (CIBJO, 2017). These pearls form within the ...

Because diamonds formed deep within the earth, under extreme heat and pressure, they often contain unique birthmarks, either internal (inclusions) or external (blemishes). Diamond clarity refers to ...

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 ...

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 ...

Garnets have been among the most popular gemstones in jewelry throughout history. They can provide a lifetime of enjoyment with proper care. - © GIA & Tino Hammid ...

美国宝石研究院 (GIA) 讲师是充满激情的教育工作者，他们将多年的行业经验带到课堂上。每个人都是其各自领域内的领军人物，每个人都致力于帮助你获得知识、掌握技能，并开启你的职业生涯。 2005 年，Stiff 在 GIA 香港分校获得了研究宝石学家 (Graduate Gemologist ...

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 ...

橄榄石、尖晶石和褐红条纹玛瑙是三种八月生日石。众所周知，橄榄石生日石是在极端条件下形成的，可在硬化的熔岩中找到。这些岩浆从地幔深处携带橄榄石而来，也可以从来自外太空的陨石中发现橄榄石。尖晶石生日石直到最近才受到人们重视，因为如今 ...