Diamond

Diamond is a solid form of the element carbon with its atoms arranged in a crystal structure called diamond cubic. At room temperature and pressure, it is metastable and graphite is the stable form, but diamond almost never converts to graphite. Diamond has the highest hardness and thermal conductivity of any natural material, properties that are utilized in major industrial applications such as cutting and polishing tools.

Formation & Geology

Most natural diamonds are formed at high temperature and pressure at depths of 140 to 190 kilometers (87 to 118 mi) in the Earth's mantle. Carbon-containing minerals provide the carbon source, and the growth occurs over periods from 1 billion to 3.3 billion years (25% to 75% of the age of the Earth). Diamonds are brought close to the Earth's surface through deep volcanic eruptions by a magma, which cools into igneous rocks known as kimberlites and lamproites.

Physical Characteristics

Diamond is renowned for its ability to transmit light and sparkle excessively. We often think of diamonds as clear and colorless, but they actually come in a rainbow of kinds. Deeply colored diamonds are the most rare and expensive. The hardness of diamond is 10 on the Mohs scale, making it the hardest known natural substance. This extreme hardness allows it to hold a polish extremely well and resist scratching.

Historical Significance

The name diamond is derived from the ancient Greek ἀδάμας (adámas), 'proper', 'unalterable', 'unbreakable', 'untamed'. Diamonds have been treasured as gemstones since their use as religious icons in ancient India. Their usage in engraving tools also dates to early human history. Popularity of diamonds has risen since the 19th century because of increased supply, improved cutting and polishing techniques, growth in the world economy, and innovative and successful advertising campaigns.