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: 2 or 3 Measurements for Gems
Frequently Asked Questions (FAQ) / Gemstone Measurement

Most of your gems have measurements like 6 x 4 x 3 mm. But I notice some have only one or two measurements, such as 5 mm or 6 x 3 mm. Why is that?

The measurements we provide are intended to represent a gemstone's length, width and depth (L x W x H) in millimeters. For many shapes, 3 measurements are needed to ensure a gemstone will fit a jewelry mounting.

For example: An oval 6 mm x 4 mm x 3 mm gemstone, would be 6 mm in length, 4 mm in width, and 3 mm in depth.

For round or square gems, only two measurements are needed since the length and width are the same (or very close). So 6 mm x 3 mm for a round or square gemstone, would indicate that6 mm is the diameter or length/width, and the second 3 mm measurement refers to the depth.

For many, the depth is not so important, so some gems may be summarized with only the length/width or diameter measurement; i.e., a 5 mm round / square gemstone).

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  • First Published: February-20-2006
  • Last Updated: March-21-2017
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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