Diamond Blemishes

Blemishes are what is seen on the face of the diamond. Chips, scratches, and the roughness of the shape’s cut are examples of blemishes, largely from an accident. Blemishes can also occur from poor manufacturing or cutting techniques. Aspects of the diamond’s face such as a rough girdle or burn marks are examples of such mistakes. Many of these can only be seen through a large magnifying glass or a loupe.

Abrasions

Abrasion is a general term for any nicks or scratches that appear at a facet junction (where two or more facets meet at a certain point). The junction will possess a white or cloudy appearance as if it has been dragged along a hard surface. Abrasions come as a result of poor handling of the stone, or if two individual diamond jewellery pieces are placed in a confined space, such as a box.

pit diamond

Pits

Pits show as a tiny white dot and are essentially a tiny surface cavity, similar to a pothole in a road. They are generally formed from the stone impacting with a hard surface, denting the stone's surface and causing this blemish to form. Pits can also be formed when a pinpoint inclusion is removed from the diamond during the polishing process, resulting in a hole where the inclusion once was.

Chips

Any part of a diamond that has been removed by due force or extreme trauma is referred to as a chip. Chips can occur in any number of ways, from something as basic as accidentally dropping the stone, through to inadequate cutting techniques. Chips, while worrying and unsightly to the naked eye, can be smoothed over and nearly completely removed through polishing.

Nicks

Nicks are smaller chips on the diamond’s surface, mostly as a result of accidental impacts. Nicks mostly occur along the girdle of a diamond. However, it is not uncommon to find them around facet junctions. Nicks is sometimes fixable through the addition of an extra facet to the shape, although this may cause its blemish later on if it is not done correctly and in proportion.

Scratches

Diamond scratches are mostly as a result of diamond jewellery being stored improperly and coming into contact with other items. Another common cause of a scratch is through poor handling, accidental impact, or grating the stone along a similarly hard surface. Scratches can happen anywhere on the diamond but are more noticeable on an individual facet.

Extra facets

Similar to its inclusion version, an extra facet is one that has been added to create more facets than the average number for that particular shape. Extra facets fall under the blemish category when they distort the diamond’s symmetry and general anatomy, normally as a result of a lack of care, or in an attempt to hide a nick through the addition of the extra facet.

Rough girdle

Any diamond girdle that appears rough or granular on its surface is considered as a blemish. A rough girdle can be one of the first signs of the diamond’s durability having been compromised if accompanied by bearding or feathering inclusions. Rough girdles can also be determined by running a finger across the girdle, where bumps, pits, and other forms of blemishes will be present to the touch.

Burn marks

Burn marks come as a result of the diamond being polished too quickly, usually resulting from an improper or hastily conducted polishing technique. If this occurs, the heat generated from the friction between the diamond and the metal jaws holding the diamond in place will create a burn mark. Burn marks can also occur if the diamond is exposed to extreme temperatures.

Surface grain lines

Also known as twin lines, these are caused by inclusions that are orientated differently from the main crystal. These will appear as two, distinct lines on the diamond’s surface, and usually run across the facet junctions in the diamond’s cut. Surface grain lines are relatively minor amongst the blemishes a diamond can suffer. They are also very faint, and can rarely be seen to the naked eye.