Where Do Diamonds Come from?

Introduction

Diamonds are a very expensive commodity. This precious gem is a favorite for jewelry but it has industrial uses as well. Diamonds are made naturally in a few different ways. This natural process took thousands of years. But scientists can imitate the natural formation process to manufacture synthetic diamonds. The need for both gem diamonds and industrial diamonds continues to grow throughout the world.

The Characteristics of Diamonds

Diamonds are made of carbon, the same material that makes coal and the lead in pencils. All life on earth is carbon-based--humans, animals and plants. Diamonds are also the hardest mineral known to man; it is almost 10 times the strength of steel. Their crystalline structure helps to disperse light, giving diamonds their brilliance. Gem diamonds are used for jewelry and other forms of decoration. Industrial diamonds have many applications, including use in oil drilling. Almost 80 percent of diamonds mined are industrial grade diamonds. To be gem grade, a diamond must meet high standards in clarity and color.

How Diamonds Are Made

Diamonds are formed 111 miles below the surface of the earth. This area is the mantle of the earth's crust, which was present when the planet was formed billions of years ago. The mantle is mostly made of molten rock and metals. When the carbon in the mantle is subjected to extremely high temperatures and high pressure, diamonds are formed. The temperature is about 2,462 degrees Fahrenheit. The high pressure comes from having 111 miles of rock on top of this high-temperature crystalline material. Other trace elements in the mantle, like sulfur and nitrogen, combine with the crystalline substance as it is formed, giving diamonds their color. Pink, yellow and blue diamonds are rare.

Other Ways Diamonds Are Formed

While most diamonds are formed in the earth's mantle, a few diamonds are created in other ways. Millions of years ago the shells and bodies of small organisms in the oceans were pulled down into the mantle of the earth by underwater earthquakes and other movements such as plate tectonics and continental drift. The bodies of these microorganisms were made into diamonds by the heat and pressure of the mantle. Diamonds were also made when meteorites impacted the planet at incredible temperatures and speeds. On rare occasions small diamonds have been found in deposits left by glaciers. These diamonds are called nanodiamonds or microdiamonds, and have been found in Indiana and Wisconsin.

How Diamonds Are Found

Diamonds reach the surface in a few ways. When volcanoes erupt, the molten lava shoots up and brings with it diamonds. The center of an extinct volcano is a good source of natural diamonds. Diamonds are also mined. The first mining began in the 1870s in South Africa which still produces some of the largest diamonds known.

Resources

• How Diamonds Are Made
• Diamonds
• American Gem Society