Turquoise is one of the world’s most ancient gems. Archaeological excavations revealed that the rulers of ancient Egypt adorned themselves with turquoise jewelry, and Chinese artisans were carving it ...

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 ...

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 ...

Ammolite is often fashioned into pendants, brooches, and earrings, and sometimes sold as objet d’art. It is not a hard stone, 3.5 on the Mohs scale, which means it can scratch easily. Heat and ...

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.

Within a short time, 90 more claims appeared in the same 20-square-mile area. No one was quite sure what the beautiful crystals were, but everyone wanted to lay claim to the profits they were certain ...

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 ...

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

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 ...

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 ...

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

Fire obsidian, so named for its vivid spectrum of colors, is rare and so far has been found in only one site within the Glass Buttes region of central Oregon. A rhyolitic dome field, Glass Buttes has ...