Luminus has developed accurate and efficient procedures in clarity grading which also incorporate finish assessments of polish and symmetry. These comprise another three grades which, along with colour and fluorescence complete the five human decisions made on every Luminus graded radiant diamond.
All the Graders must offer approval for all estimates in clarity, brilliance and regularity grading. This is best provided in plotting appropriate symbols for features observed in or upon a polished diamond on a plot template. A grade most often corresponds visually to its graphic representation or the number, size and location of icons on the plot diagram.
Round brilliant cut
The standard round brilliant has 57 Facets consisting of 1 table, 8 stars, and 16 upper girdle facets situated on the upper side or the crown of the diamond. 16 lower facets and 8 pavilion facets are situated on the pavilion side of the diamond. An additional culet facet would then total 58.
In the interests of accuracy and simplicity, Luminus graders plot or comment only upon features that serve to set a diamond’s clarity grade and ignore all others. Only clarity lineaments, grading reviews, naturals and extra facets show up on the grading report’s diagram.
A Bruise is a nick with a feather located underneath. Often resulting from impact damage a bruise is generally located on a facet rib. Bruises are very small features, generally limited to VVS and VS1, and are irrelevant on VS2 and SI clarity diamonds.
A Cavity is the hole left when an included crystal falls out during polishing, the hole left by polishing open a gas bubble, or an indented natural that is not located on a facet rib or the girdle.
A Chip is a hole on the girdle, facet junction (rib) or culet left from serious impact damage or a feather breaking out of a polished diamond. Significantly larger than a nick, a chip is considered a clarity feature unless at the cult where it is considered in a diamond’s polish grade. Appearing more like broken glass, a chip has less crystal form than an indented natural.
A Cloud is a hazy or milky area consisting of minute inclusions or a closely arranged group of small inclusions such as pinpoints, needles or crystals. Clouds may be specific in dimension and location or they may be dispersed and take up large areas in a diamond.
A crystal is an entirely included diamond or other mineral crystal. In plotting, Luminus graders have the choice of 6 standard sizes of crystal. Use of the small crystal eliminates any grade better than VS1. A medium crystal precludes any grade better than VS2 and the large crystal precludes any grade better than SI1. Diamonds with highly contrasting crystals readily visible to the unaided eye through the pavilion against a light background may be graded I-1 and lower.
An etch channel is a linear feature and is usually the hole left over from another mineral either being burned or acid boiled out.
A Feather is an included fracture or crack that may or may not follow a natural cleavage direction. It may be totally included or reach the surface of the diamond and appears whitish or transparent. The allowance is made in grading VVS clarity surface feathers as having less impact upon a grade than fully included pinpoints, needles or clouds.
Winding It up
So, whether it is a radiant diamond or a perfect round cut diamond. At Luminus, we extensively check and then double check the quality of diamond to cater the best quality diamond for your customers.