这一组原石和成品蓝宝石显示了蓝色至紫罗兰色或紫色色彩的广泛范围，以及可以在约戈蓝宝石中发现的由淡到深的色度组合。最大的刻面宝石是一颗 1.44 克拉的垫型切工宝石。由 Bill Vance（比尔·万斯）友情提供。摄影：Kevin Schumacher（凯文·舒马赫） 尽管美国 ...

During the past 25 years, the corundum market has been transformed from one of medium to high-priced gems to one that encompasses nearly all price ranges. This transformation was caused by 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 ...

GIA has studied more than 400 important gemstones in the Edward J. Gübelin Gem Collection and is committed to sharing this repository of gemological information. Dr. Edward Gübelin’s lifelong study of ...

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 ...

Jadeite comes in a wide range of colors. The most valuable is an intense green called Imperial. - Courtesy Mason-Kay Fine Jade Jewelry To understand the value of jade, you have to look beyond its ...

Those born in January are lucky to have the beautiful and diverse garnet as their birthstone. Garnets are commonly red but also come in an extraordinary range of beautiful colors, including orange, ...

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 ...

A GIA Report is not a guarantee, valuation or appraisal, and GIA makes no representation or warranty regarding its Reports, the articles described therein or any inscription thereon. A GIA Report ...

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.

Emerald, the birthstone for May, has been beloved for millennia, evoking rebirth and renewal. Widely regarded as the definition of green, emerald is the perfect color for spring. From the poetic ...

Some natural opals, mostly from Ethiopia, show a macroscopic finger-like structure called a digit pattern. This pattern consists of vertical columns that are more or less parallel, separated by a ...