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Diamonds are among nature’s most precious and beautiful creations.

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Colorless diamonds are scarce—most diamonds have tints of yellow or brown.

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Factors used to describe diamonds: Clarity, Color, Cut, Carat Weight

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The rarity of one or more of the 4Cs can affect value.

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The crystal shape of a gem diamond is often the octahedron.

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Trigons—little triangular depressions—occur only on octahedral faces.

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Growth marks

Diamond’s growth marks help experts separate diamonds from simulants.

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Buyer's Guide

Few consumer products undergo the scrutiny that diamonds are subjected to. That’s because subtle variations in color, cut and clarity can cause significant differences in a diamond’s value.

How to Choose a Diamond


Use your zip code to find a jeweler near you with GIA reports and GIA-trained staff.


Verify the information on your report matches what is archived in the GIA report database.

What To Look For

Diamond Examples on the GIA Color Scale
Color: The amount of a diamond's color, on a scale of D-to-Z

GIA’s D-to-Z scale measures the colorlessness of a diamond, comparing it to masterstones under controlled viewing conditions.

Diamond Clarity Grade
Clarity: The relative absence of inclusions and blemishes

Clarity grades are based on the number, size, relief, and positions of inclusions that can be seen under 10x magnification.

Diamond Clarity
Cut: Can affect diamonds’ brilliance, fire, scintillation

Precise workmanship is required to cut a diamond so its proportions, symmetry, and polish maximize brightness, scintillation, and fire.

Differences in Diamonds
Carat Weight: Diamonds are sold by weight

One carat is equal to 0.20 grams. Only one in 1,000 diamonds weighs more than a carat.

Diamond Quality Factors: The Comprehensive Guide

Tips & Advice

1. Insist on a diamond grading report.

The differences in diamond quality can be so subtle even a trained jeweler can't recognize them without lab verification. Insist that any diamond you buy comes with an indisputable verification of its quality from an unbiased source.

2. Protect your purchase.

Have your diamond appraised and insured. Appraisers and insurers rely on diamond grading reports to accurately evaluate the value of gems. As an additional measure, consider having your diamond laser-inscribed with its GIA report number, to provide verification if it is ever lost or stolen.

3. Look for a gem that weighs a bit less than your target size.

Prices per carat generally increase as the weight passes “magic numbers” such as 1.00, 1.50, and 2.00 carats. A diamond that weighs 0.95 carat will cost less per carat than a 1.00 carat stone but look almost the same.