Diamond Carat Weight Guide

We're here to help as you shop for the perfect diamond.

Diamond Carat Weight Guide


Setting the Stage

“Wow, that diamond is huge! How many carats is it?” a friend might ask their recently engaged bestie. The friend in this hypothetical scenario may be shocked to discover that the diamond is 1.0 carat, but looks bigger because it's surrounded by a halo of sparkling diamonds. 

A diamond’s carat is a measurement of weight, but as the carat size increases, so too does the appearance of the diamond, especially when comparing diamonds of the same shape. If you’re in the market for a sparkling new diamond ring, carat weight is an important concept to understand before making your purchase. We created this Diamond Carat Weight Guide to help you understand diamond carat size and what to look out for during your next ring shopping experience. To narrow down the perfect carat weight for you or your fiancée-to-be, keep reading!

What Is a Diamond Carat?

To fairly assess the quality and value of every diamond, each is measured on four cardinal attributes — cut, clarity, color, and carat (or the 4Cs). Of these, carat has one of the biggest effects on the overall appearance of a diamond in relation to how small or large it looks after being placed in a setting and slid onto your ring finger.

Often described as an increment of size, a diamond carat is actually a measure of weight, with one metric carat equaling 200 milligrams or one-fifth of a gram — the world standard since 1914. A diamond carat is then broken down into 100 segments called points, with one point corresponding to .01 carat. For example, a 0.56-carat diamond would be 56 points.


A sorting tray of loose diamonds

Diamond Carat vs. Size

While mass and weight share a positive correlation with one another, it is important to remember that diamond carat weight is not the sole measurement of a stone's size. Other attributes of the stone, such as shape and cut, can have a dramatic influence on how large the stone appears regardless of carat weight.

Two round diamonds of identical carat weight can be cut differently, changing the visual appearance of their size. One may be cut shallow, resembling a plate or saucer, while the other may be cut with deep, drastic angles, looking more conical in form. Once in a setting, the plate-shaped diamond will likely look larger than its conical counterpart. Fancy-shape diamonds can further distort the relationship between carat weight and size, appearing much larger or smaller than their round diamond counterparts.

Diamond Carat Chart

While diamond carats are a measure of weight and not size, it is true that heavier diamonds will appear larger if other attributes like cut and shape remain equal. The following diamond carat size chart provides an idea of how a diamond will look from the top down, depending on its shape and carat size. Keep in mind that your individual diamond may appear differently depending on its unique cut and other physical features.


Origin of the Diamond Carat System

Human discovery and trading of diamonds predates even the invention of scales and units of mass, leaving diamond traders to come up with other methods of determining the value of their wares. In ancient times, diamonds were weighed using the small seeds of the carob tree, which were considered to be uniform in weight. As the means of measuring weight advanced through history, the system stuck. 

The weight of a carob seed evolved into the carat weight we know today, which is 200 milligrams as determined at the fourth General Conference of Weights and Measures. Now, ultra-precise electronic scales take the place of carob seeds and rudimentary tools as gemologists measure the carat weight of each diamond to the hundredth decimal place for exacting valuations.

A diamond engagement ring and two wedding bands

Diamond Carat vs. Price

A diamond with a higher carat weight will typically cost more than one with a lower weight, but a diamond’s value is still dependent on other factors like cut, clarity, and color. When comparing diamonds with the same specifications, however, a 1.0-carat stone is worth more than the value of four 0.25-carat stones added together. If stones have different evaluations for cut, clarity, and color then two diamonds of identical carat weight can sell for very different prices.


Diamond Carat Buying Tips

  • Consider finger size. If you’re shopping for engagement rings, the size of the diamond isn’t the only thing that matters. Its ratio to the size of the finger it ends up on is also important. For example, a 1.0-carat solitaire will look larger on a size six finger than on a size eight finger.
  • Consider fancy shapes. For a larger diamond that fits a smaller budget, fancy-shape diamonds fit the bill. Not only are they visually stunning, but they’re also less expensive than traditional round diamonds of the same carat weight.
  • Dispel magic tricks. In the industry, benchmark carat weights — half carat, three-quarter carat, and carat increments — are known as magic sizes. Because of the increased rarity, there is a significant price bump at every magic size a diamond surpasses. However, the average fiancée-to-be won’t be able to tell a 0.95-carat stone from a 1.01-carat stone by size only — unless they see the receipt!
  • Prioritize cut. A diamond’s brilliance depends on how it is cut, not its weight or size. This may sound strange in an article about the importance of diamond carat weight, but if sparkle is your endgame, cut is more important than carat. In fact, larger diamonds require higher grades on the other three Cs to appear high-quality.
  • Shop for the best of all worlds. Less than one percent of all diamonds meet our exacting specifications for Shane Classic diamonds. With top marks in each of the 4Cs, you sacrifice nothing in terms of quality and end up with a keepsake that is as unique as your love.

With carat weight demystified, why not learn more about diamond quality to increase your knowledge and likelihood of finding that perfect diamond for you. Or, if you feel ready to dive right in (don’t worry, knowledgeable Shane Co. consultants are just a click away), check out our diamonds and diamond engagement rings.


A woman wearing a diamond engagement ring