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 ...

However gem quality diamonds are fashioned from the original crystal shape they possess a combination of brightness, sparkle, fire, and sense of purity not matched by other gems. - Jeff Scovil, ...

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 ...

This amethyst crystal is from Namibia. It shows classic quartz crystal shape: a six-sided columnar crystal with a pyramid-shaped termination at the top. Courtesy Daniel Trinchillo, Fine Minerals ...

Citrine is one of the most popular yellow gems on the market. This designer cut shows off the warm glow of citrine’s sunny color. – Lydia Dyer, gem courtesy John Dyer & Co. Citrine—the transparent, ...

Diamonds have a long history as beautiful objects of desire. In the first century AD, the Roman naturalist Pliny stated: “Diamond is the most valuable, not only of precious stones, but of all things ...

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 ...

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 ...

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 ...

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, ...

Figure 1. A single tourmaline fiber contains three distinct chemical zones, each recording the fluid composition at the time of growth. Between zones, fluids dissolved preexisting tourmaline to ...