How to Tell the Carat Weight of a Diamond

Carat weight is important when it comes to diamonds, as the overall size of the gem is one of the defining characteristics that will determine its overall value. Depending on the level of accuracy you require in your determination, there are a number of ways to ascertain the carat weight of a diamond, ranging from simple (and generally free or cheap) to complex (and more expensive). Always choose the more precise methods if you need an official appraisal of your jewelry, but if you only need to know for personal edification, less accuracy is required.

Things You'll Need

• Flexible tape measure

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Instructions

• 1

  Use an approximation guide (see "Carat Weight Chart" in Resources) to compare the size of your diamond with others similarly sized to determine a general estimate for the carat weight of your gemstone. This is the least accurate method to determine carat weight, but it is also the swiftest, so use it in a pinch where you simply want a general idea of the size of your diamond.

• 2

  Measure your diamond with a flexible tape measure. Measure the length and width of your diamond along the top (in millimeters) and the depth (also in millimeters). You will also need to know the cut of your diamond (e.g., round, pear-shaped, princess cut). Input these into a carat weight calculator (see Resources) to determine the weight of your stone. This is a good method when you need an estimate of carat weight but are unwilling to spend money on a professional assessment.

• 3

  Take your diamond to a professional appraiser. This service is normally offered at both chain and independent jewelry stores, or you can look for a completely independent appraiser. Use this method when you require an absolutely accurate appraisal and are not worried about cost. A professional appraiser can give you certification of your diamond's characteristics, which is useful if you need authentication for potential buyers.