Carbon flaw

A carbon flaw is a blemish present within a diamond crystalline form of carbon, usually seen as a black spot. The blemish may be microscopic or visible to the naked eye. These spots are undesirable imperfections since they can be seen easier than other flaws. It is worth noting that, while diamonds are composed of purely carbon, the black spot flaws could be other inclusions (foreign matter) such as titanic iron or hematite.

Appearance

Carbon flaws can come in many different appearances. They can range in size from specks so small they can barely be seen with the a magnifying glass to spots and clusters clearly visible to the naked eye. A carbon flaw can appear as a sharply defined spot or as an amourphous cloud, like a shadow in the stone. The appearance of a spot usually indicates an inclusion of uncrystalized carbon, whereas a cloudy carbon flaw is indicative of improper or irregular crystalization. Carbon flaws can also appear as small, fuzzy dots, somewhere betweeen a speck and a cloud. Another common carbon flaw appears as a black shard or needle through the stone.

File:Heavily Spotted diamond.jpg

A heavily flawed diamond.

These flaws are regarded as undesirable in any stone. The presence of these flaws can severely impacth the value of the stone, despite it's carrat weight. Most flaws that do not effect the clarity or brilliancy of the diamond are usually seen as ugly and will drive buyers away from a stone. The flaws that do effect brilliancy make it hard to sell a stone at any price.

Formation

The reason for the formation of carbon flaws is largely unknown. It is theorized that, though the material was exposed to the same conditions of heat and pressure as the rest of the crystal, there may be some other factor not evenly distributed throughout the carbon that formed the diamond. Many chemical actions happening simultaneously could possibly cause carbon in the solution to surround particles that escaped the solvent. Another thaeory is that diamonds are formed by the slow accretion of crystals. This means that the crystal structure forms and grows around a sinlge nucleus of the element and that nucleus can be excluded from the crystalization process. This nucleus is then surrounded by crytalized diamond and becomes a carbon flaw. These nuclei are theorized to be other common forms of carbon such as graphite or carbonado, though they could be an amorphous carbon structure.