How to Determine Loose Gemstone Size to Fit a Ring Setting

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Things You'll Need

  • Jewelry calipers or gauge

  • Loose gemstone

  • Ring setting (with measurements in millimeters)

  • Pen

  • Paper

  • Cloth

Image Credit: Comstock/Comstock/Getty Images

Loose gemstones offer customers the ability to design their own unique and beautiful ring. By choosing the cut and color for the gemstone, as well as the ring setting, you're sure to create something that will be one-of-a-kind. Whether you are making or designing a gemstone ring, learn how to measure the faceted stones so they fit your desired ring setting.


Measuring Loose Gemstones

Step 1

Lay a cloth down on your workstation, to protect the stone and setting.

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Step 2

Measure across the width of the stone with calipers or a gauge. Place the stone in the calipers and gently slide the gauge until the stone is secure. Read the measurement in millimeters and write down the results.

Step 3

Measure the length of the stone in the same fashion and note your results. For example, a heart-shaped stone would be measured from the tip of the heart to the top for the length, and horizontally across the upper part of the stone, where the heart shape is widest.

Step 4

Verify your measurements and stone shape with those of the ring setting, which are usually given in millimeters. For example, a rectangular setting for an emerald-cut stone could be 10x8mm, while a large heart stone might have the same millimeter measurement but a different shape.


If you don't have calipers or a gauge, you can estimate the size of the stone with a ruler, but this will give a less accurate reading. Round stones need only be measured across their widest part.


Be careful not to drop or exert undue pressure on the stones with the calipers, as some gemstones can be fragile.


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