Explore tourmaline history, research, quality factors, and more in the GIA Gem Encyclopedia.

These environmental stresses create a unique "fingerprint" within each natural diamond that is only visible under deep-UV light. Much like the growth rings of a tree, these patterns tell a story of ...

The Panyu district is a leading gemstone cutting and jewelry manufacturing center for the global gem and jewelry industry. Situated near Hong Kong, it plays a key role in jewelry exports from mainland ...

Previously we introduced sapphire as a gemstone and as a major industrial material that spurred the advancement of many synthetic crystal growth techniques. Synthetic sapphire is commonplace in our ...

Another way to measure a ring is to take a measurement of the inside and determine the finger size from a standard chart. The inside of the ring must be perfectly round for this to work.

GIA invented the science of grading diamonds with the 4Cs and the International Diamond Grading System ™ – standards used by jewelry professional around the world. So there’s no better place to study ...

Full quality assessment, color grade and clarity plot. Identifies natural vs. treated color. For loose, natural, colored diamonds 0.15 carats or more.

Gem and mineral hardness is measured on the Mohs scale. The numbers are based on the relative ease or difficulty with which one mineral can be scratched by another. But the Mohs scale is deceptive.

Natural mint-green chrysoberyl, much of it extremely clean, is also found in Ilakaka, Madagascar; Sri Lanka; and Mogok, Myanmar. Prior to this study, there had been very little investigation into ...

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 ...

Quality Assurance Benchmarks highlight workmanship of semi-finished or finished jewelry. Learn how to evaluate the quality of a platinum ring that has been prefinished, polished, and buffed.

Zircon is rated 6 to 7.5 on the Mohs scale. It has fair to good toughness. While zircon is not as hard or tough as a stone like sapphire, it can still be worn in all types of jewelry as long as proper ...