Surface graining is lines on the surface of a diamond, caused by irregularities in its crystal structure. It is like internal graining, but on the surface.
In more detail
It is a blemish. It comes from the crystal itself, not from damage or from polishing.
On a grading report
A blemish; it is not always plotted.
Related terms
- Internal graining: Internal graining is lines, angles or curves inside a diamond caused by irregular crystal growth. At 10x they can look whitish, colored or reflective, or lower the transparency.
- Polish lines: Polish lines are fine parallel grooves and ridges left by polishing. They can occur on any facet but don't cross facet junctions, and they look transparent or white.
- Blemish: A blemish is a clarity characteristic confined to the surface of a diamond.