Lower-quality turquoise is softer and more porous and is often treated to make it durable enough to wear. Fine turquoise is naturally beautiful – because it is rare and in demand, it is more valuable.

You can send your diamond to GIA for grading and analysis. Many consumers send the diamond through a retailer for packaging, shipping and insuring the item. A jeweler will have to remove your diamond ...

GIA fully supports the Kimberley Process Certification Scheme and upholds its principles. In 2000, GIA began working closely with the World Diamond Council (WDC) as they led the international diamond ...

7月の誕生石であるルビーの意味、歴史、産地について詳しく学びましょう。

Non-nacreous non-bead cultured pearls from the Pinctada maxima mollusk are characterized and compared with pen pearls in order to aid in origin separation.

Madagascar has become one of the world’s top sources of fine blue sapphire in recent times. In addition to beautiful untreated material, increasing numbers of treated stones have appeared in the ...

The history and geology of the Swat deposit were comprehensively reported by Arif et al. (2011) and Giuliani et al. (2019) and are summarized here. However, a detailed study of the inclusions and ...

This 6.30-carat black boulder opal from Queensland, Australia, displays vivid play-of-color. Black opals are highly valued because their dark body tone showcases play-of-color more dramatically than ...

Christopher M. Breeding, Sally Eaton-Magaña, and James E. Shigley ...

When a diamond falls outside of GIA’s D-to-Z color scale, it is considered a colored diamond (sometimes called a fancy-color diamond). This includes all colors other than colorless to light yellow or ...

Part 2 of 5 in the series: Value Factors, Design, and Cut Quality of Colored Gemstones (Non-Diamond). This article establishes a common language for discussing cutting styles, with a focus on basic ...

With a reach that spans the globe, GIA is a nonprofit institute dedicated to protecting consumers by ensuring their trust in gems and jewelry through cutting edge gemological research, rigorous ...