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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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About Diamond

Diamond forms under high temperature and pressure conditions that exist only about 100 miles beneath the earth’s surface. Diamond’s carbon atoms are bonded in essentially the same way in all directions. Another mineral, graphite, also contains only carbon, but its formation process and crystal structure are very different. Graphite is so soft that you can write with it, while diamond is so hard that you can only scratch it with another diamond.

Diamond Description

Diamond History and Lore

Diamond Journey

Birthstones & Anniversaries

On almost all modern birthstone lists, diamond is recognized today as the birthstone for April. Diamond is also the gem that marks the 60th and 75th wedding anniversaries.

58x Harder

Diamonds are the hardest material on earth: 58 times harder than anything else in nature.

“Lucy” in the Sky

Fifty light years from earth, this star is a 10 billion-trillion-trillion carat diamond.

1 in 1,000,000

The average yield in most diamond mines is 1 part diamond to 1 million parts host rock.


  • Mineral: Diamond
  • Chemistry: C
  • Color: Colorless
  • Refractive Index: 2.42
  • Birefringence: None
  • Specific Gravity: 3.52 (+/-0.01)
  • Mohs Hardness: 10


There are a number of processes used to alter the color, apparent clarity, or improve the durability of gems.

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Some gemstones have synthetic counterparts that have essentially the same chemical, physical, and optical properties, but are grown by man in a laboratory.

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Any gem can be imitated—sometimes by manmade materials or by natural materials chosen by man to impersonate a particular gem.

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gem love

Why We Love This Gemstone

Global Language

The 4Cs, created by GIA, are considered the global language of diamond quality.


Diamond is the only gem composed of one single element: carbon.

A billion years

Most diamonds formed more than a billion years ago, deep in the earth’s mantle.

Quality Factors

The human contribution to a diamond’s beauty is a well-executed cut.


quality factors

Clarity grades assess the number, size, relief, and position of inclusions and blemishes.


quality factors

The less color, the higher the grade. Even the slightest hint can make a dramatic difference in value.


quality factors

Cut (proportions, symmetry, and polish) is a measure of how a diamond’s facets interact with light.

Carat Weight

quality factors

Rarity means larger diamonds of the same quality are worth more per carat.

Diamond Quality Factors: The Comprehensive Guide


Explore research on diamond history and diamond grading.

Rough CLIPPIR diamonds

The Very Deep Origin of the World’s Biggest Diamonds

Evan M. Smith, Steven B. Shirey, and Wuyi Wang , Jan 26, 2018 Read Article
The round brilliant is the most popular diamond cut. Because of its popularity, assessment of this cut has been the subject of considerable research. Courtesy of Harold & Erica Van Pelt.

Diamond Cut: The Wow Factor

Amanda J. Luke , Jan 14, 2016 Read Article
Diamond from Jericho eclogite and Juina superdeep diamond

Diamonds from the Deep: How Do Diamonds Form in the Deep Earth?

Karen V. Smit and Steven B. Shirey , Feb 1, 2019 Read Article
Diamond Fun Facts

Diamond: Fun Facts

, Nov 24, 2015 Read Article