Stone Weight Terminology

It should be noted that although we use diamonds in our examples, most of the terminology and examples described here can be applied to most color stones as well.

If you're going shopping for a diamond, you should know the basic terminology relating to weight. As you learned from the "The 4C's of Diamond Grading" video on carat weight, 1 carat = 200 mg = 1/5th of a gram. However, most gemologists don't use grams or milligrams when talking about diamond sizes, they use carats or points interchangeably. Here are a few examples:

  • 100 points = 1 carat
  •   50 points = 1/2 carat
  •   25 points = 1/4 carat
  •   10 points = 1/10 carat
  •     1 point   = 1/100 carat

So, when discussing diamonds with a professional, you might hear a 1 carat diamond referred to as a "hundred pointer", or a 10 carat diamond referred to as a "10 pointer"

It's important to note that carats are not the same as size since diamonds of the same carat weight with different cuts may appear slightly different in size.

We strongly recommend that you not purchase any diamond that's over 1/2 carat (50 points) unless it's certified by a reputable grading lab.

Jewels and Gems