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Ask The Experts: Carat Weight


Diamond Size: How much does carat weight influence the price of a diamond?


The first factor of the 4 Cs that most people learn is carat weight, which is the best indication of a diamond’s size. Let’s take a minute to cover carat weights in detail to understand how it effects the price.


Diamond weights are measured in “carats.” One carat equals 1/142nd of an ounce, or 1/5th of a gram. In other words… there are 142 carats in 1 ounce and 5 carats in 1 gram.

The word “carat” comes from the ancient practice in India (where diamonds were first discovered and traded) of measuring diamond weights with the one thing in nature that is both small and the most consistent in weight — the carob seed. Thus the name “carat” evolved in the English language, which is still equivalent to approximately the weight of one carob bean.


You also may have heard jewelers talking about “points” when discussing diamond sizes. This does not refer to the number facets on a diamond, but rather to its weight. Just like one pound is divided into 16 ounces, one carat is divided into 100 points — so each point is 1/100th of a carat. A “10-point” diamond weighs 1/10th of a carat, and a 50-point stone weighs one-half carat.


Carat weight has a great deal of influence on the price of a diamond — more so than one might imagine at first. Since larger stones are more rare in nature, they are more expensive as well. For instance, one diamond weighing 2 carats will always cost much more than two diamonds of the same quality weighing 1 carat each.

Below is an approximate comparison of the major diamond weights to act as a starting point in your consideration.

Diamond Sizes

IMPORTANT: Monitors vary widely.
Hold an actual dime over the picture of one below. If the dime below is actual size, then the diamond sizes in this chart are accurate for your monitor.

Knowing the 4 Cs is NOT enough to price a diamond accurately.

At least 13 factors affect diamond value, including fluorescence, table percentage, symmetry and other crucial details.

To find a price on any diamond, use our Diamond Price Tutorial Page, which teaches you how to use online diamond databases to calculate what to pay for any diamond. If you cannot find a good jeweler, we rate the top dealers for you.