Clarity Grading

 

We use a number of terms to describe the clarity grading of our gems. Please note that all clarity grades assume a typical indoor lighting situation, which should not be extremely bright (such as direct sunlight or directly under a light source) or very dim (candle light, mood lighting or similar). A typical residential room with indirect natural light from windows or electric light, or typical office lighting would be a good reference.

 

Here is a list of the terms we use and descriptions of them:

 

Loupe Clean: The gem has no obvious inclusions when viewed with a standard jeweler’s loupe at 10x magnification in typical indoor lighting. There may still be tiny inclusions or clarity characteristics visible at this level.

 

Eye Clean: The gem has no obvious inclusions to the naked eye in typical indoor lighting. There will likely be some small inclusions visible at 10x magnification with a standard jeweler’s loupe.

 

Lightly Included: There will be some small, but eye-visible inclusions in typical indoor lighting.

 

Moderately Included: The gem will have some inclusions that are obvious to the naked eye in indoor lighting.

 

Heavily Included: The gem has many obvious inclusions. We don’t typically cut gems that are this included, but the term is here for reference.

 

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Color Grading

 

Color-Change - A color-change gem has an optical phenomenon that causes it to appear different colors in different temperatures of light.  Alexandrite is a famous color-change gem, appearing green or teal in cool white or daylight and red, purple in warm light.  The color-change effect is fairly common in sapphires, and occurs in many other gem species.

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Bi-Color / Multi-Color - This term indicates a gem with multiple colors present in it, typically caused by color zoning.

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Zoning / Zoned - Color zoning in a gem is when there are areas ("zones") or bands of different colors.  It's caused by changes in the growing conditions of the crystal when it originally formed.  The zones may be soft with a smooth shift to a new color, or sudden with bold, stark color differences.

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Dichroic / Trichroic - An optical property of crystals and gems, broadly called "pleochroism".  This optical effect causes the gem to appear different colors based on the direction that light passes through it.  In a cut gem, as the light changes direction as it passes through and is reflected by facets, it may show the other color(s) or a mixture of the colors.  A dichroic gem can show two different colors, and a trichroic gem can show three.  Dichroic and trichroic gems polarize light as it passes through them, and the effect is more apparent when viewed through a polarizing filter.  It's important to note that while this is a totally different cause of multiple colors in a gem from zoning or color-change, a gem can be dichroic/trichroic and also zoned, color-change, or all three!

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Treatments

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If a gem has any treatment, it will be clearly disclosed in the details of the stone on the product page for the gem.  We currently only sell gems that are natural or heat treated.

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Heat - This is a common, routine treatment on many gem species.  Sapphires and rubies are among the most commonly heat treated gems.  Aquamarine, tourmaline and zircon are also commonly heat treated.  Heating may be at low or high temperatures depending on the situation and gem species.  It is a permanent treatment.

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Heat & Flux - This is a less common form of heat treatment, but it involves heat treating at high temperatures with a flux chemical which acts to dissolve the gemstone slightly, helping to seal fractures and voids that may be present.  It is considered a permanent treatment as the gem material is actually dissolved and reformed, "healing" the fracture.

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Irradiation - This involves treatment with various sources of radiation, which can alter the color of some gems. The color alteration from the treatment may or may not be permanent.  Blue topaz is a commonly irradiated gem, and the color is considered permanent.​

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Clarity Enhanced - A gem with fractures can have its clarity improved by filling the air gaps in the fractures with a transparent material (liquid, resin or glass).  It is a very common treatment for emeralds.  This treatment is not typically considered permanent, as the filling agent can be removed or damaged by heat/solvents.

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If you have any questions about our grading or terminology, please contact us at: info@aprgemworks.com

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