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: Color Change Gems
Frequently Asked Questions (FAQ) / Color Change Gems

Why do some gems show a color change?

Color Change Gemstones Color change gems have two approximately equal sized transmission windows. A blue gemstone appears blue because it absorbs all frequencies of light except for blue. A gemstone that absorbs both blue and red light will appear blue when the light is rich in blue wavelengths (e.g. in sunlight or fluorescent light) and red or purple when the light is rich in red wavelengths (e.g. in incandescent light).

View all of our color change gemstones here.

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  • First Published: February-20-2006
  • Last Updated: August-03-2017
  • © 2005-2018 all rights reserved.
    Reproduction (text or graphics) without the express written consent of (SETT Company Ltd.) is strictly prohibited.
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Size and Weight

Gems are always measured in Millimeter (mm)

Dimensions are given as;
length x width x depth,
except for round stones which are;
diameter x depth

Select gems by size, not by weight!
Gem varieties vary in density, so carat weight is not a good indication of size

Note: 1ct = 0.2g

Size Comparison Chart