If you have a diamond-studded family heirloom or are looking for the perfect engagement ring, knowing the carat size will help you determine the value of the diamond. Verify the size of the stone independently to avoid an overzealous jewelry dealer taking advantage of you. Find a jeweler who has a policy that allows you to purchase the diamond, get the size verified on your own, and return the diamond if the carat size given is incorrect. You can measure it yourself, but it is best to go to an appraiser.
Use a tape measure. This is the least accurate way to determine measurement, but it will give you a general idea of your diamond carat weight. Find a tape measure that measures in millimeters. Set the diamond face up on a clean flat surface. You are measuring the diameter of the diamond at the widest point. This will be different depending upon the shape of your diamond, but generally it is the girdle area of the diamond. The girdle area is the widest point around the diamond, and typically separates the crown, or face, of the diamond that is visual in a jewelry setting from the part of the diamond that is not visible in a jewelry setting. Lay the beginning of the tape measure next to the diamond on one edge and stretch the tape measure tightly past the other end of the diamond. Measure to the very last edge of of the diamond. When you have a number, you can convert the millimeter measurement into carats using a conversion chart or online conversion tool. For example, a 4.1 mm diamond is .25 carats.
Print out a carat size comparison chart. This is less accurate than a tape measure, but will give you a general idea your diamond's carat size. You will find a size comparison charts on many diamond jeweler's websites. Look for one that has chart sizes for the different shapes, such as the round brilliant cut and the square princess cut. Once you have printed out the chart, place a loose diamond directly on top of the visuals until you find the closest match. It will tell you the size of your diamond by millimeters and carat weight. If your diamond is in ring form this will be harder to do, so you will have to eyeball it more or less.
Take your diamond to a diamond appraiser. This is the best way to know the exact size of your diamond. Diamond appraisers have been trained to measure diamonds and have special industry tools to give you the absolute, most accurate carat size. It is best to go to an independent appraiser who has no incentive for exaggerating about the size of your diamond, unlike a jewelry store. Go to an appraiser who has been verified by the Better Business Bureau and has a graduate gemologist diploma from a reputable gemology education institution, such as the Gemologist Institute of America.
How to Buy Diamond Jewelry in Vietnam
How to Measure a Gemstone
How to Tell If a Gem Is a Kunzite?
How to Measure Pearls
The Value of Commercial Grade Diamonds
How to Add Diamonds to the Bezel of a ...
How to Negotiate on Jewelry
Tanzanite Vs. Diamonds
Does Gold Jewelry Have to Be Stamped?
How to Resize a Stainless Steel Ring
How to Find Out What My Baccarat ...
What Is TDW Diamond?
How to Buy Diamond Jewelry in Cambodia
How to Resize Palladium Rings
Cubic Zirconia Vs. White Spinel
How to Determine the Width of Faces
How to Prepare for a Nose Piercing
How to Clean Diamond Rings With ...
Eagle Scout Etiquette Gifts
What Is 18 Carat Gold?
Based in Los Angeles, Zora Hughes has been writing travel, parenting, cooking and relationship articles since 2010. Her work includes writing city profiles for Groupon. She also writes screenplays and won the S. Randolph Playwriting Award in 2004. She holds a Bachelor of Arts in television writing/producing and a Master of Arts Management in entertainment media management, both from Columbia College.