Diamonds, being a natural product, are subject to imperfections. Diamond Clarity grading is a system that has been developed to categorise and describe these imperfections. Refer to the chart on the right for a range of clarity grades used by the GIA (Gemological Institute of America)
Types of Imperfections on Diamonds
The internal imperfections are broadly called inclusions, and the surface irregularities are called blemishes. Taken together they are the 'clarity characteristics' of the diamond. The following table categorises and explains the various imperfections found in diamonds:
Abrasions - Small nicks on facet junctions or on the culet caused by wear or rubbing against other diamonds.
Naturals - portions of the rough crystals surface left on the finished diamond usually in the girdle.
Extra Facets - Small facets created to remove imperfections that are not part of the cutting style.
Polish Marks - Surface clouding caused by excessive heating during polishing.
Polish Lines - Small parallel lines left by irregular polishing.
Surface Graining - Faint lines causing wavy or grooved surfaces due to irregularities in crystal growth.
Rough Girdle - Caused by poor workmanship.
Bearding - Small feathers extending inward from a bruted girdle surface.
Cavities - Large/deep openings in the diamond's surface.
Chips - Small/shallow openings in the diamond's surface, respectively.
Clouds - Hazy or cloudy areas caused by numerous very small inclusions.
Feathers - White and feathery cleavages or fractures.
Fractures - Breaks along planes other than cleavage planes.
Included Crystals - Mineral crystals, such as garnet or peridot, contained within a diamond.
Indented Naturals - Natural rough surfaces that penetrate the stone and can distort the girdle's outline.
Internal Graining - Regions of irregular crystal growth appearing as milky or coloured lines & streaks. May also be reflective.
Needles - Needle shaped included crystals.
Pinpoints - Areas of minute pinpoint inclusions.
Twinning Wisps - Clouded areas produced by distorted crystal formation.
Laser Drill Holes - A minute tube made by a laser. Resembles a needle.
Whilst inclusions decrease the value of a diamond they are useful in that they allow a gemologist to identify a diamond using the unique combination of its inclusions. Inclusions also make it possible to distinguish real diamonds from lab created ones.
All other factors being equal, the higher up the chart a diamond's clarity grade is the more valuable it is. Diamonds between the grades of VVS1 and SI2 represent the bulk of the retail market.