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  1. Natural Diamonds | Diamond Stone – GIA C

    Get to know all you need about diamond – the history, facts, quality factors, treatments, imitations and much more here at GIA.

  2. Diamond Description

    Diamond forms under high temperature and pressure conditions that exist only within a specific depth range (about 100 miles) beneath the earth’s surface. Diamond’s crystal structure is isometric, which …

  3. Diamond History and Lore

    Diamond’s splendor has been appreciated for centuries, but there was not much scientific knowledge about it before the twentieth century. Since then, diamond knowledge has grown steadily, with …

  4. Home | GIA 4Cs

    While choosing a diamond is a very personal decision, evaluating a diamond should always be a matter of precision. At GIA, we are incredibly proud that our 4Cs of diamond quality continue to educate the …

  5. GIA Diamond Grading Scales: The Universal Measure of Quality

    Mar 14, 2013 · The prospect of purchasing a diamond may seem daunting, but through GIA, an unbiased authority on diamonds, you have several handy resources to help you select the highest …

  6. The Extraordinary Backstory of Natural Diamonds: A Diamond Is (and …

    May 3, 2024 · Examines new developments in the story of diamond formation and their extraction from the earth.

  7. A Study of the Winston Red: The Smithsonian’s New Fancy Red Diamond

    Presents the first scientific and historical study conducted on the 2.33 ct Winston Red, the fifth-largest known Fancy red diamond in existence.

  8. Guide to Diamond Engagement Ring Shapes | GIA 4Cs

    Nov 21, 2025 · Explore the GIA Guide to Diamond Engagement Ring Shapes and learn the differences between round, oval, marquise and more. Make a well-informed decision when choosing the perfect …

  9. Understanding the 4Cs of Diamond Quality - GIA 4Cs

    This framework is both a way to better understand your diamond, and to ensure accuracy in the evaluation of your diamond’s unique characteristics. It is the best way to ensure clear information, …

  10. Digging into Diamond Types - GIA 4Cs

    Jul 9, 2014 · In the 1930s, scientists first began to use two categories to describe a diamond’s chemical composition and atomic structure: type I and type II. Now these categories are further subdivided into …