Skip to main content

Diamond Inclusions & Blemishes

Diamond Inclusions

Inclusions are internal clarity characteristic of a diamond.

crystal Sometimes a diamond contains a mineral crystal that looks like a bubble or black spot and this feature is called crystal.
needle A long and thin crystal.
pinpoint A tiny crystal that appears like a dot.
cloud A grayish patch that consists of a group of pinpoints.
twinning wisp A ribbon like inclusion on the diamond’s growth plane.
internal graining Irregularities in crystal growth may cause some lines or textures that appear like haze on the diamond surface.
grain center Although not visible from every angle, grain center looks like a transparent tornado inside the diamond..
feather Any break in a diamond. There are two types: cleavage is a break that is in a cleavage plane, and fracture is one that is in any other direction. Feathers can get larger with a hard knock and thus considered more problematic than any other inclusion.
bearded girdle Fine feathers scattered around the diamond’s perimeter. If it’s heavy, it can go all the way around the stone.
bruise A small tree-root like feather caused by a hard blow.
knot A shallow opening on the surface caused by damage after cut and polish.
chip A ribbon like inclusion on the diamond’s growth plane.
cavity A deep opening with visible drag lines at side.
indented natural A part of the rough diamond surface that goes below the polished diamond surface and leaves triangle shaped or parallel grooves.
laser drill-hole A tiny tunnel shaped inclusion caused by laser beam process.

Diamond Blemishes

Blemishes are external clarity characteristic of a diamond.

abrasion Small nicks on the facet caused by mishandling of the stones. It can happen when diamonds rub against one another.
pit A tiny cavity that looks like a white dot.
nicks Small surface chips caused by wear.
lines Visible lines at surface that run across facet junctions.
naturals A part of the rough crystal surface that was not polished on the polished stone. They are usually on or near the girdle. If the term “indented natural” is used, that means the natural extends onto the crown or pavilion.
scratches and wheel marks Scratches are caused by improper storage of the diamond in the diamond paper or contact with other diamonds. If diamond is polished without care, grooves called wheel marks can occur.
extra facets Facets placed on a diamond to polish out small blemishes like a natural or nick. They may be additional to any facet needed for a specific cut style. Extra facets don’t affect the clarity grade.
rough girdle A girdle surface that is irregular, pitted, and sometimes chipped. This can be a sign of weakness.
burn marks Marks caused by either too fast polishing or a real heat source. It can be polished out.