Gemological Institute Of America | We Grade The World's Most Precious Diamonds, Including Yours

Graded by GIA

A Brilliant Legacy

From the Hope diamond to the Spirit of the Rose, the Taylor Burton and the Lesotho Promise, we are trusted by museums and top auction houses all over the world to grade and research nature’s finest treasures.

We apply the same passion, precision and expertise that we use in grading these world-famous diamonds to grading every diamond – including yours.

Explore famous diamonds graded by GIA

Report Number: 6207143699

Color: D

Carat: 302.37

Clarity: VVS1

Lesedi la Rona

Courtesy: Graff

Report Number: 5230103

Color: Fancy Dark Grayish Blue

Carat: 45.52

Clarity: VS1

Hope Diamond

Courtesy: Smithsonian Institute

Report Number: 10159998

Color: M

Carat: 127.01

Clarity: VS1

Portuguese Diamond

Courtesy: Smithsonian Institute

Report Number: 45497

Color: E-F

Carat: 69.42

Clarity: IF

Taylor-Burton Diamond

Courtesy: Photo by Gianni Bozzacchi. Reprinted by permission.

GIA's 4Cs

Get Clarity with the 4Cs

Know what you are getting in the moments that matter most. Each GIA-graded diamond comes with a GIA report that details important quality information about the diamond, including the 4Cs.

Cut

Cut evaluates a diamond’s proportions, facet placement and symmetry. These factors are important because they affect a diamond’s brilliance, fire and face-up pattern. It ranges from Excellent to Poor.

Color

Color measures a diamond’s absence of color and is graded on a D-to-Z scale. Each diamond is given a letter grade that falls into a color category from “colorless” to “light.”

Clarity

Clarity is based on a diamond's inclusions. Inclusions are often natural crystals trapped within the gem or other characteristics from a diamond’s formation that make a diamond unique. Grades range from Flawless to Included.

Carat

Carat measures the weight of a diamond. Each carat is equivalent to 0.2 gram, meaning a 5 carat diamond weighs 1 gram. The modern carat system started with the carob seed. Now, the carat system is standardized and used in every corner of the world.

The New GIA App

Diamond Knowledge at Your Fingertips.

Learn how the 4Cs affect appearance and value via videos, articles and interactive tools. Save and organize diamond reports, or create a diamond wish list-all with the new GIA App.

Download now at:

App Store^® and Apple^® logo are registered trademarks of Apple Inc., Google Play and the Google Play logo are trademarks of Google LLC.

From The 4Cs Blog

Unearth Diamond & 4cs Knowledge

Copyright: GIA & Harold and Erica Van Pelt

VVS DIAMOND VERSUS VS DIAMOND

Clarity grades can impact the value of your diamond, but how much do they impact appearance? Learn the difference between VVS and VS diamonds.

TIPS FOR BUYING AN ENGAGEMENT RING

Get brilliant about how to purchase an engagement ring. Here are some tips on how to pick the perfect center stone and setting.

Courtesy: Chip Clark, Smithsonian Institution

IS DIAMOND FLUORESCENCE GOOD OR BAD?

Did you know that some diamonds glow or fluoresce under long-wave UV light? Learn how and when florescence impacts a diamond’s appearance.

Courtesy: Sotheby's

WHY ASK FOR A GIA GRADING REPORT?

We don’t sell diamonds. As an independent research and educational institute, our mission is to protect the public and deliver objective, impartial science-based information about diamonds and gemstones.

Copyright: GIA & Tino Hammid. Courtesy: Benjamin Zucker

ORIGIN OF WEDDING RINGS

Did you know that the tradition of exchanging wedding rings dates back to Roman times? Learn the motifs, metals and stones that lovers used throughout history to pledge their love and commitment.

Discover Brilliance

We Grade the World’s
Most Precious Diamonds,
Including Yours.
Feel confident you're choosing the best
with a diamond graded by the experts at GIA.