A blemish is a clarity characteristic confined to the surface of a diamond.
In more detail
Polish lines, scratches, nicks, pits, abrasions, naturals and extra facets are blemishes. They can count in the polish grade as well as in clarity. An Internally Flawless stone has blemishes only.
On a grading report
On GIA's plot, naturals are green and extra facets black. Many minor blemishes are not plotted; Comments can mention them.
Related terms
- Inclusion: An inclusion is a clarity characteristic inside a diamond, or one that reaches the surface from inside.
- Internally Flawless (IF): Internally Flawless (IF) is the clarity grade for a diamond with no inclusions at 10x. Only blemishes on the surface show.
- Polish: Polish is the grade for the smoothness of the facet surfaces, from Excellent to Poor. The grader looks at 10x for pits, nicks, polish lines, scratches, burn marks and rough patches.
- Natural: A natural is a part of the rough diamond's original surface left on the cut stone. It is usually on or near the girdle.
- Extra facet: An extra facet is a facet that the cutting style doesn't need, placed without regard for the stone's symmetry. It is most often near the girdle.