How Can I Estimate the Carat Size of My Diamond?

Getting a diamond -- whether you are purchasing it for yourself or receiving it as a gift -- is very exciting. One of the first questions people will ask about it is simple: How big is it? If your diamond didn't come with a Gemological Institute of America (GIA) or other identification certificate, or if it was a gift, you may be unsure of the carat weight. But there are ways that you can estimate the carat weight without having to remove the ring from the setting to weigh it.

Instructions

1

Find a device that can measure millimeters (mm). Digital calipers that measure millimeters make measuring diamonds easier because you can fit the calipers around the gemstone and the size is presented on a digital screen. Digital calipers can cost anywhere from $12 to $100. You can also use a traditional ruler that has millimeters, but it can be difficult to get the ruler around the stone to take a precise measurement.

2

Measure your stone, in millimeters. If you are using digital calipers, the mm measurement will appear on screen. If you are using a ruler, be sure it is graded in millimeters. Millimeters are 1/10 of a centimeter.

3

Compare the millimeter measurement to a diamond measurement chart. These can be found at almost any online diamond retailer site or in most jewelry stores. Keep in mind that the shape of your stone matters. For instance, a one-carat round diamond generally measures around 6.5 mm, while a one-carat princess generally measures approximately 6 mm. That means that well-cut round stones typically face up larger for their carat weight than fancy cuts like the princess, cushion, or asscher.