以下是 GIA 将休业的法定假期列表。 2025 年 5 月 5 日（星期一） 玛哈•哇集拉隆功国王陛下加冕（补假） 2025 年 5 月 12 日（星期一） 卫塞节（补假） 2025 年 6 月 3 日（星期二） 王后陛下诞辰 2025 年 7 月 10 日（星期四） 守夏节 ...

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 ...

Resources for Careers in Gems & JewelryGIA Career Services maintains an up to date database of U.S. and international job offerings in the jewelry industry. Employers from every industry sector list ...

Attain your dreams of a GIA education with a scholarship. We encourage on-campus students to apply for assistance and we are happy to help you coordinate your efforts. GIA-administered scholarships ...

In an effort to help you understand the GIA Cut Grading System more fully, and to make the best use of it in your business, we provide these informative charts and booklets that summarize the system, ...

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 ...

Diamond is the only gem made of a single element: It is typically about 99.95 percent carbon. The other 0.05 percent can include one or more trace elements, which are atoms that aren’t part of the ...

GIA identifies the country of origin by requiring the diamond be received and examined in rough form in a sealed, tamper-proof package directly from the mine. Data is collected on the rough and each ...

Gemological LibraryResources The library provides a wide variety of gemstone-and-jewelry-related resources for students, staff, researchers, alumni, members of the industry, and the general public.

In colored stones, transparency and clarity are closely linked. This is especially true for emeralds. The trade generally accepts eye-visible inclusions in higher-quality emeralds. But when the ...

Figure 1. Yellow, brownish gray, and near-colorless anorthoclase feldspar from southeast Vietnam. The rough stones range from 96.5 to 144.8 ct and the cut samples from 3.64 to 11.07 ct. Photos by Le ...

GIA On Campus and accelerated programs and lab classes are available in Shenzhen through a cooperative program at Peking University Resource College. Programs and classes are taught by GIA instructors ...