Back to top Geologic Occurrence Diamonds have been found in many different localities throughout the world, but there are only a few place that have a notable amounts. Diamonds are found often in alluvial deposits, as this mineral accumulates and weathers well because of its inert chemical nature, extreme hardness, and fairly high specific gravity. Kimberlites or lamproites are the igneous rock types in which diamonds are found in primary deposits. Hardness is related to bonding of the carbon atoms. Brilliancy is a result of index of refraction.
Fire is created from diamond's high dispersion.
The most valuable diamonds are flawless and completely colorless. A faint yellow color, which is the most common color, detracts from the value. If the diamond occurs in a deep shades of yellow, red, green, or blue, they are known as fancy stones. Diamonds can be artificially colored by radiation, heat, or by being exposed to high speed electrons. These resulting colors can be very hard to distinguish from naturally formed colors.