Carat Weight

The first factor of the 4 C’s that most people know is carat weight, which is the best indication of a diamond’s size. t’s time to understand how the weight effects the price. It is more complicated than assuming larger diamonds cost more. They actually cost more “per carat”.

It just happens, that the best way to know diamond size, is to SEE diamonds if you can. To find local stores you can trust, search here for stores I have tested :: local jeweler reviews.


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.

Just for fun, let’s calculate diamond value against the price of apples. Fuji apples are about $1.40 a pound (if not organic). If we take 142 carats per ounce, 16 ounces to a pound, and 1.00 carat G/VS2/Ex round brilliant diamonds are about $7,700 per carat, then…. a pound of diamonds would cost about $17,494,400.00. Yes, that is 17 million dollars. [I love figuring out that stuff.]

The word “carat” is believed to originate 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 “Point / Points” when discussing diamond sizes. This does not refer to the number of 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. Perhaps it comes from saying the decimal weight out loud such as “that is a point one oh carat diamond”. [Just my theory.] A “10-point” diamond weighs 1/10th of a carat, and a 50-point stone weighs one-half carat.

Here are some images to give you some idea of 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 might be fairly accurate for your monitor.




Another attempt at diamond sizes, just for comparison, and not to be considered accurate to scale.



Carat weight has a complicated effect on the price of a diamond.

Since larger stones are more rare in nature, they are more expensive as well. But not just in direct proportion to their size. The price actually goes up faster than the weight. Much faster.

For instance, one diamond weighing 2.00 carats will always cost much more than two diamonds (of the same quality) weighing 1.00 carat each. So in diamonds, 1 + 1 does NOT equal 2, when it comes to price.

Here is the page in the Diamond Pricing Tutorial on How Carat Weight Affects Price, for the details.


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