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Grading Scale

 
There is no standard accepted grading scale for colored gemstones (like there is for diamonds). As such, there is A LOT of confusion when it comes to interpreting individual vendor's grading. This page will thoroughly explain our grading scale, and hopefully you'll agree our scale is thorough enough to meet your needs. And easy enough to understand.

Our grading scale is broken into 3 major sections. But first we state our Overall Grade (out of 5 possible gems). The overall grade is formed based on a combination of the color, cut and clarity of the gem. The 3 major sections are Color, Cut, and Clarity.

Color
We describe the color in three parts: the actual color name, the depth of the color, and the quality of the color. The color name consists of two parts: the modifier and the MAIN COLOR. For example (violet Blue), is a Blue color with violet modifying it.

The depth of the color describes how pale or dark the color actually is, and we graphically represent that on a scale from Dark to Light. Depending on the type of gem, a medium tone is most expensive. Individual tastes do vary.

The color quality describes the consistency of the color, including if there is any color banding, zoning, or any other color inconsistencies that would be of interest.

Cut
We describe the cut in four parts: the shape and cutting style, the symmetry, polish & finish, and windowing of the gem. The shape and cutting style may be something like Round Brilliant. The round describes the shape, while brilliant describes the faceting technique applied to the stone.

The symmetry is graphically represented from poor to excellent, depending on the symmetry of the gem. There are various elements of symmetry depending on the style of cut, may include if the table is even and centered, if the stone is exactly round or slightly out of shape, etc...

The polish & finish of the gemstone is also graphically represented on a scale from poor to excellent. This describes if the facet junctions are precise. Also, if there are any wheel marks or polishing marks left on any facets. Also, if there are any problem facets, such as abraded areas, would be factored into this grade. An excellent stone would have no issues. A very good grade would have minor issues, maybe related to some facet junctions not being precise. Any obvious wheel marks or polishing errors would bring it down to a poor or fair grade.

Windowing describes the ability to see through the stone from the face (table). A very shallow stone will look like a window (you can see right through the stone and out the other side). A very nice cut may allow the light to reflect so you can't see out the back side of the gem when looking through the gem face up. Our scale graphically represents how much of a window is present (0-5% none, 5-10% slight, 10-20% medium, 20-35% fair, 35%+ poor). Some cutting styles and shapes will have unavoidable windows.

Clarity
The clarity scale is graphically representing the amount and severity of the inclusions from worst (Heavy) to cleanest (very very lightly). Other Vendors may have a scale that goes to IF (internally flawless) -- essentially, this is the same as our very very lightly included grade. The IF (internally flawless) grade is generally looked down upon by the elite color gemstone grading labratories and experts. Also, many vendors will grade clarity at NO magnification. We grade our gems' clarity at 10x magnification.

If you have more questions about our grading scale, or would like to know why a stone was graded a particular way, please don't hestitate to contact us. Email sales@riogems.com or phone-in toll-free at 1-866-746-4367.