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A Comparison of Diamond Size on the Finger

How we measure diamonds


When it comes to buying a diamond, one of the most important factors to consider is the size of the stone. However, it can be confusing to understand the different measurements used to describe diamond sizes. Here's a breakdown of the most common ways diamonds are measured and what they mean.

Carat weight


The most widely used measurement for diamonds is the carat weight. One carat is equal to 0.2 grams, and diamonds are often sold in fractions of a carat. For example, a 0.5-carat diamond would be described as a "fifty pointer" or "a half-carat". The price of diamond increases exponentially with carat weight, so a one-carat diamond will typically be more expensive than two half-carat diamonds of similar quality.


Comparing diamond sizes


Watch our recent video to view some of the popular diamond sizes on the hand—from 4mm (0.25 carats) to 8mm (2 carats).

Diameter


Another measurement used to describe diamond size is diameter—the width of the diamond measured from one edge to the other. We use this measurement for round diamonds, as their shape makes it easy to measure accurately. A typical one-carat round diamond will have a diameter of approximately 6.5mm. Sometimes, a round diamond certificate shows two diameter measurements. This double measurement accounts for microscopic differences in the diameter across the diamond. 

Table Percentage


The table percentage is the ratio of the diameter of the diamond's flat top facet (known as the table) to the diameter of the entire diamond. This measurement is used to describe the overall appearance of the diamond, as a larger table percentage will make the diamond appear larger. However, a high table percentage can also affect the diamond's brilliance and fire. This detailed information typically appears on diamond certificates and reports created to provide assurance for buyers. 


Depth Percentage


The depth percentage is the ratio of the height of the diamond (measured from the table to the culet) to the diameter of the diamond. This measurement is used to describe the diamond's overall proportions and can affect its brilliance and fire. A depth percentage that is too high or too low can make the diamond appear dull or dark.