Diamonds are formed when at depths of between 130 and 200 kilometres beneath the surface of the earth. They are naturally produced as the mineral carbon crystallises under intense pressures and temperatures. The volcanic activity ultimately pushes the diamonds up through the volcanic pipes.
During the diamond formations, internal features develop in the stones, and these are commonly referred to as inclusions. Enclosed minerals form alongside the diamond, non-crystallised carbon or fractures. The number and type of inclusions could lower the value of the cut diamond; however, they can also have positive effects.
For example, the study of inclusions can separate a natural diamond from stimulants, can provide scientists with more information on how diamonds are formed, and as no two stones have the same inclusions it is easier to identify individual gems.
Flawless diamonds are extremely rare and therefore are very expensive. Stones which have inclusions that are visible to the unaided eye are significantly cheaper. Most jewellery stones often fall between these two extremes, as they have inclusions which are only visible when examined under 10x magnification.
Diamonds can also have surface irregularities which can be known as blemishes, and this can include nicks, scratches and the original crystal face left on the cut stone's surface.
|Internally flawless||Very, very small inclusions, very hard to locate under 10x magnification, and not visible to the unaided eye.||Very small inclusions, difficult to locate under 10x magnification, and not visible to the unaided eye.|
|Small inclusions, relatively easy to locate under 10x magnification, but not seen with the unaided eye.||Piqué (inclusions visible to unaided eye)|
In addition to internal characteristics, diamonds can also have surface irregularities known as blemishes. These include scratches, nicks and areas of the original crystal face left on the surface of the cut stone.