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Meaning & Significance of Diamond Carat Weight

When people talk about how many carats a diamond has, they are actually referring to the diamond weight, not the diamond shape or size. When you compare diamond carat sizes it’s important that you also consider each diamond’s cut. A diamond with a larger carat weight may appear smaller than a smaller carat weight diamond if the diamond cut is poorly done and/or deeper. The same applies to diamonds of equal carat weight.

You should take our Expert Diamond Buying Tips (see below) to heart when shopping for cut diamonds. And, if you also refer to our Diamond Carat Size Chart (also below), you should be able to select the best diamond shape and diamond carat weight in your price range.

Diamond carat weight is how many metric carats a diamond weighs. A carat is equal to 200 milligrams.

Each carat of a diamond can be subdivided into 100 different “points” in order to precisely measure it. Each point is a unit of weight. If a diamond weighs less than one carat, the number of points it has is used to describe it. For example, a jeweler might use the phrase “twenty-five pointer” to describe a diamond with 0.25 carats.

Expert Diamond Buying Tips:

• Remember that carat refers to a cut diamond’s weight measurement, not its shape or size.
• Cut and carat should be considered together when comparing diamonds. A larger carat diamond that has been poorly cut (lower cut grade) will look smaller to the naked eye than a smaller diamond that has been expertly cut (higher cut grade.)
• Jewelers consider some diamond weights as “magical.” These are the ½ carat, ¾ carat and the 1-carat diamonds. The naked eye cannot see any difference between a full-carat diamond and a 0.99-carat diamond, but the difference can certainly be felt in the pocketbook!
• To get the most from your money it is suggested that you “buy shy” by choosing a diamond that weighs slightly below ½ or 1 carat. For example, rather than a full-carat diamond with 100 points, you might want to select a 0.95 diamond carat weight. This will save you quite a bit of money and no one will ever notice the difference.
• Remember that the prices of diamonds can increase exponentially. The larger the diamond in terms of carat weight, the more it will cost due to its rarity. Diamonds with higher weights cost more money. That’s just a fact.

Diamond Carat Size Chart

This chart shows the differences among diamonds of various carat weights. Your diamond may be different than those shown on the chart in terms of table, depth, and length to width ratio.

download chart

In measuring the carat weight of a diamond, two factors are taken into consideration:

1. Diameter Across the Top

A measurement, in millimeters, is taken across the diameter at the top of the diamond because this is the part that’s seen once the diamond is set into the ring.

2. Cut Grade of the Diamond

The diamond’s cut grade is also considered because a beautifully cut diamond will reflect the light much better at the top, which makes it look larger. A well-cut diamond is graded “very good” or higher.

How would these two weight measures help you when making a purchase?

The diameter of the diamond, along with its cut grade, clearly shows that smaller carat weight diamonds look larger when they are well cut, with a “very good” or “ideal” cut grade. On the other hand, a diamond with a larger carat weight can easily look smaller if it has a lower cut grade of “poor,” “fair,” or just “good.”

 

Additional Tips from the Experts:

• If you’re on a limited budget, but diamond carat size is of primary importance, you may want to look at “good” cut diamonds with a clarity of SI1 or SI2 and color grades of I or J.
• Diamond prices increase dramatically once you’re a diamond carat weight at the ½ carat mark and full-carat mark. Diamond weights slightly below either of these weights will be priced significantly less since the weight is measured over the entire diamond. Small differences in weight or size are nearly impossible to see.
• It goes without saying that a diamond is going to look larger on someone with a slender finger. A 1-carat diamond solitaire will appear a lot larger on someone with a size-4 finger than on someone with a size-8 finger.
• You need to know that not every setting will fit every diamond carat weight or diamond shape. If you already know which setting you want, make sure that the diamond you select will fit and stand out well in that setting.