"Colored stones grading" is used by the industry in general to establish a benchmark in comparing Faceted gemstones. It breaks down into many categories depending on: Color, Clarity, Cut, Carat. New Directions use a sliding scale from A to Gem for the grading of our gemstones. When you are comparing Cabochon gemstones there is no real establish grading. We have established a four-tier guideline for the grading of cabochons (See Cabochon Gemstones in the table below) from Cab A to Cab Gem. The scale is based in order on the following priority: Cut, Gem Material, Coloration, and Clarity (For additional information go to the bottom of this page).

FACETED GEMSTONES

CABOCHON GEMSTONES

CABOCHON GRADING

First, in order of priority, these are the things to consider in grading cab materials (as well as facet materials that have been cabbed).

1. Because of the primarily non-optical properties of most cabbing materials, the cut is of top importance.It should be either an even, uniform dome following a single arc from one edge to another, or perfectly flat.If the material is a faceted cabochon or a rose cut, the faceting must hold to the same standards as typical GEM faceted stones.The girdle edge must not be less than 90 degrees (either a flat bottom with a vertical edge or a tapered edge) to facilitate use in jewelry.The polish must be as high as possible for the material as well as uniform in appearance.
2. Next comes the quality of the primary attribute of the gem material, whether it be asterism, chatoyancy, clarity, plechroism, or the primary attribute of its inclusion, ie. well formed tourmaline needles, visible insect, symmetry of rutile star burst.If it is an inclusive attribute, it should be well centered or placed within a plane of symmetry of the stone.
3. Coloration is third in materials which coloration or an aspect of coloration is not the primary attribute.In dichroic or trichroic materials there should be a clear distinction between colors.In monochromatic materials the color should be even throughout the stone.
4. Clarity.In translucent cabochon materials clarity usually comes into consideration only so far as uniformity is concerned.It refers to the homogenous level of opaquity within the stone when lit from underneath.In transparent cabochon materials the clarity is given the same considerations as in a typically faceted stone.

Of course there are some exceptions, but this applies to the vast majority of materials. The major exceptions are stones such as druzy materials in which cutting takes virtually no part, and stones such as fire agate where coloration and polish, not cutting is top on the list.