True Weight

Weighing the Facts:

The “True Weight*” of Diamonds

One-carat diamonds offered for sale rarely truly weigh one carat if cut correctly.

Let me explain. Diamonds are a lot like people. They come in all shapes and sizes, and just like people, they can carry a little extra weight. In fact, in the community of diamonds, more diamonds are “overweight” than in the community of people: Up to 88% of all diamonds. The sad part is that it’s the diamond industry that is purposely producing all of these chubby diamonds! In 1919, over 90 years ago, a gentleman by the name of Marcel Tolkowsky determined that the diamond industry as a whole was cutting diamonds incorrectly and adversely affecting the diamond’s sparkle. Mr. Tolkowsky released a paper on the correct way to cut a diamond so it would have maximum sparkle (light return); no excess body fat. The Tolkowsky cut ended up becoming the American ideal. Subsequently, in the 1950’s, a gentleman by the name of R.W. Ditchburn applied the same mathematics in order to trim the fat off the other shapes (marquise, pear, oval, etc.). For decades if you asked for a well cut “Ideal” diamond of a particular size, you got it. Then the marketeers convinced the public that a one carat diamond or more was the dream size. That’s where the problems crept in. Diamond cutters all over the world started inventing their own criteria for “a well proportioned stone” so they could fatten up the diamond. Clearly we have a problem when 75% to 88% of all one carat diamonds are overweight! Just like in the Wendy’s commercial where there was a whole lot of bun and very little meat, we are running into the same problem today with diamonds that should be 1 carat but are cut fat so they will tip the scales over one carat.

Solution: The only way the problem is going to be solved is for the diamond buying public to start asking for the diamond’s “True Weight,” (a diamond in which the crown height plus max girdle thickness plus pavilion depth equals the total depth percentage and whose proportions meet class I or class II criteria.) I’ve never met a jeweler who will volunteer to the consumer that the device used to measure the diamond’s vitals (sarin or megascope machine) also has a fat content measuring button! It’s called the re-cut feature. Once a diamond has been analyzed, all the grader has to do is enter the recorded data into the re-cut program, enter the desired results, (like a plastic surgeon showing you what your nose will look like after the surgery) and click the mouse. In seconds the re-cut program will announce what the diamond should have weighed if it had been cut correctly vs. its current weight. Practically every diamond I see is overweight by 20%-30%!

It is the diamond’s “TRUE WEIGHT” we should be paying for, not extra love handles left on by the cutter. If enough of us demand to only pay for a diamond’s “True Weight” versus its “over-weight” then maybe some day the cutters will get the message.

*If you would like to determine your diamond’s “True Weight,” please call the National Diamond Helpline at
1-800-275-4047 with your diamond’s vitals and we’ll tell you what your diamond should have weighed.

by Fred Cuellar,
author of the best-selling book “How to Buy a Diamond.” More questions?
Ask the Diamond Guy®