Shopping BasketImperfections, Irregularities and Blemishes
A diamond's external imperfections or irregularities - those that are confined strictly to the surface of a diamond - are often referred to as 'blemishes'.
When your diamond is graded, its individual characteristics will be marked on your certificate. These characteristics may be on the diamond's external surfaces or internal in the diamond crystal itself.
Listed below are some terms used to describe external blemishes found on a diamond's surface - it may be interesting for you to read on and find out what they mean:
'Abraded' facet edges or culet
Resulting from heavy wear and tear over a long period of time. It will appear white frosted or to have a sandblasted look which under magnification can be seen as a series of minute nicks.
Burn Marks
Can result from friction during the polishing process creating a cloudy or frosted surface area. They may also occur during repair, from the heat of a jeweller's torch.
Cavity, Nick or Pit
An opening in the polished surface of the diamond that would cause a loss of carat weight if removed.
Chip
A shallow opening into the diamond stone usually with an uneven or stepped surface. Severe chips can alter the outline of the diamond.
Extra Facet
Placed without regard to a stone's symmetry, extra facets are commonly used to polish out minor blemishes. When not visible directly through the crown, they are not considered a blemish but would still be marked on a plotting diagram. An extra facet will be polished with straight edges and polishing lines. In some cases, where facets over and above the normal number have been added as part of the cutting style, "additional facets" can be used or may be described as, for example, "modified brilliant" or "modified princess cut".
Girdle Roughness
Resulting from rough or fast bruting of the girdle.
Grain Lines
These result from irregularities in natural crystallisation.
Naturals
Remnants of the original rough diamond's surface which are left on the polished diamond, frequently on or near the girdle. While these are blemishes, they indicate a sign of skilled cutting, as the cutters try to spread the stone and retain as much of the original crystal's weight as possible. In many cases, naturals do not affect the clarity grade, but when found on or near the girdle, the stone's girdle directly opposite should be examined as a corresponding natural is often found there. Naturals are proof that the stone is indeed a natural diamond.
Indented Natural
A natural which interrupts the girdle of the diamond but would cause weight loss if polished out.
Percussion Marks
Result of a sharp blow to the diamond's surface, creating an indentation with very small cleavage fringes. Often seen as small white spots on the edges between facets.
Polishing Lines
Polishing lines may appear as parallel irregularities on the surface of the gem but are rarely heavy enough to lower the clarity grade of a diamond. However, visible polishing lines will diminish the diamond's 'finishing' grade.
Scratches
Fine white lines as the result of diamonds coming into sharp contact with each other.
