The characteristics of a diamond that extend from the surface to the interior are called "inclusions". The common diamond inclusions mainly include the following.
Whisked Waist: Small feather cracks that extend inward from the surface of the waist, possibly originating from the cutting and grinding process.
Stasis marks: small areas caused by external force impact, accompanied by root like feather cracks; Generally seen at the intersection of facets.
Hole marks: Angular notches caused by the rupture of a part of a feather crack, or the drop of crystals near the surface or extrusion during polishing.
Gap: A shallow opening formed on the surface of a gemstone by trauma, occurring at the edge of the waist, at the intersection of the facets, or at the pointed bottom.
Cloudy substance: Many tightly packed and indistinguishable needle point inclusions, with an overall appearance resembling a cloud or mist.
Feather cracks: A general term for internal cracks in gemstones, often appearing as white feathers.
Twin center: A small cluster of twisted crystals that can appear white or dark in color, resembling a linear or needle shaped appearance.
Crystal: The mineral crystals contained within a diamond.
Inner concave natural surface: Part of the original stone surface is concave below the surface of the cut diamond.
Internal twin stripes: Stripes, angles, or arcs that appear white, colored, or reflective, or affect transparency at ten times magnification, caused by irregular crystal growth.
Internal laser drilling: Surface feather cracks caused by laser drilling inside diamonds, or expanding existing feather cracks around dark inclusions to the surface of diamonds. Injecting bleach into the crack of the feather can reduce the visibility of the contents.
Crystal Knot: White or transparent diamond crystal inclusions that touch the surface of a cut diamond.
Laser hole: A small pore created by a laser beam that touches the surface.
Needle shaped object: A slender crystal resembling a thin rod under a 10x magnifying glass.
Needle point: A small crystal that appears as a dot under a 10x magnifying glass.
Double crystal network: A series of needle points, clouds, or crystals formed at the growth site of a diamond; Accompanied by crystal distortion and twin planes.