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Diamond

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

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Color

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

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4Cs

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

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Rarity

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

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Octahedron

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

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Trigons

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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Tools

Overview

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.


Facts

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

Where It's Found

map

Treatments

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

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Synthetics

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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Imitations

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

1
Global Language

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

2
Carbon

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

3
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.

Clarity

quality factors

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

Color

quality factors

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

Cut

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

Research

Explore research on diamond history and diamond grading.

The Cullinan Diamond Centennial: A History and Gemological Analysis Of Cullinans I And II

Kenneth Scarratt and Russell Shor , Jun 1, 2006 Read Article

GIA’S Symmetry Grading Boundaries for Round Brilliant Cut Diamonds

Ron H.Geurts, Ilene M. Reinitz, Troy Blodgett, and Al M. Gilbertson , Dec 1, 2011 Read Article

Color Grading “D-to-Z” Diamonds at the GIA Laboratory

John M. King, Ron H. Geurts, Al M. Gilbertson, and James E. Shigley , Dec 1, 2008 Read Article

An Examination of the Napoleon Diamond Necklace

Eloïse Gaillou and Jeffrey E. Post Read Article