How to Measure a Gemstone

by SaraHaley ; Updated September 28, 2017

The measurements of a gemstone can give you an idea as to its worth and value.

garnet gemstones image by Julianna Olah from

Maybe you're a jeweler at a local jewelry store and need to measure a loose gemstone. Or perhaps you're looking at making jewelry and need to fit a gemstone to a certain ring or necklace. There are many instances where you may find yourself needing to know how to measure a gemstone, either by weight or size. There are a numebr of techniques to help you properly measure a gemstone either for jewelry use, appraisal or personal knowledge.

Measure the diameter of a gemstone by using a caliper, either a manual one or a high quality, electronic calibrated one. This will tell you the diameter of a the gemstone, which is essential if using the gemstone in a jewelry setting or for a specific use.

Determine the carat weight of a gem. This is one way to measure a gemstone to determine its worth, and can be done with a special, highly sensitive gemstone scale. A carat weighs .2 grams (or in U.S. measurements, .007 ounces), so it is important to have a special gem scale in order to properly determine the carat measurements of a gemstone.

Estimate the size of a given gemstone by using a stone gauge or hole gauge. These are rulers or templates with varying sizes of holes in which you can pass a gemstone through to estimate its approximate diameter and size. This does not, however, help you determine the carat weight of a gemstone, but can be helpful for a jeweler that is trying to fit a gemstone for a particular setting.

Invest in a Leveridge gauge, which can help you measure gemstones with extreme accuracy. Leveridge gauges appear like a scale that you would see at a supermarket for produce, but have a caliper on the top, so you can not only measure length and width, but weight as well. This can be used for measuring gemstones in or out of a jewelry setting.


  • Measuring gemstones that are loose is easier and less complicated than measuring a gemstone already in a setting.

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About the Author

Sara Haley has been writing professionally since 1998, writing articles for companies such as "Planned Parenthood." During her senior year in high school, she wrote for "The Papillion Times," "The Gretna Breeze," and other local newspapers. She also writes for her own sites, Omaha Moms and Happy Apping, andstudied in English and journalism at Metropolitan Community College.