Skip to Content Skip to Navigation

Diamond Carat

Carats and diamonds have been linked to each other for thousands of years. The modern carat system originated with early gem traders who would use carob seeds as counterweights in their balancing scales. At the time, each country had its own system and measurements would vary, but a universal agreement in 1907 officially made 1 metric carat = 200 milligrams.

Today, as part of the 4Cs, carat is still an essential part of determining the value of a diamond — and communicating that value to shoppers. Whether you’re shopping for an engagement ring or the perfect pair of diamond earrings, here is what you should know about the role of carat weight in diamond jewelry.

Diamond Carat Weight Measuring Chart

People often mistake carats as a measurement of size, but they it actually measures weight (CTW = Carat Total Weight). Modern diamonds are cut with machines so it’s possible to measure each one to the nearest 0.01 ct. With that kind of precision, we know that within each carat range, diamonds will be an average size in millimeters:
Carat Weight Millimeter (mm) Size
A 0.05 carat diamond 0.05 carat 2.5mm
A 0.25 carat diamond 0.25 carat 4.1mm
A 0.50 carat diamond 0.50 carat 5.2mm
A 0.75 carat diamond 0.75 carat 5.8mm
A 1.0 carat diamond 1.0 carat 6.5mm
A 1.25 carat diamond 1.25 carat 6.9mm
A 1.5 carat diamond 1.5 carat 7.4mm
A 2.0 carat diamond 2.0 carat 8.2mm

Diamond Carats and Price

Out of all the 4Cs, carat weight has the largest impact on the price of a diamond. That’s why a diamond cutter’s top priority is to maximize weight, therefore producing a more expensive stone. Sometimes cut quality suffers in favor of keeping the stone at a very precise, more desirable size.

The other three 4Cs: color, clarity, and cut can change the value of a diamond, so it’s important to take all four into consideration before making a purchase.
Diamond Carat Weight Measuring ChartDiamond Carat Weight Measuring Chart

How Carat Impacts Jewelry

Carat and diamonds will always be linked. Still, regardless of budget, not all styles of jewelry require the largest carat available. While a diamond engagement ring may call for one stone as a centerpiece, diamond bracelets and necklaces are usually a combination of smaller stones. Carat weight for diamond earrings can also vary depending on the style of earrings.

Carat weight may be the largest factor in determining price, but it’s also the easiest factor to compromise on when you have a budget to stick to. From choosing a stone that isoff size to opting for a combination of smaller stones or a piece that incorporates gemstones, there is more than one way to find the diamond jewelry of your dreams.

The Other 3CsThe Other 3Cs

The Other 3Cs

What diamond cut is best for you?

Let’s get clear about flaws and inclusions.

Evaluating the color of a “colorless” diamond.

Join Our Email List & Receive a Special Offer