What is a round brilliant cut diamond?
By Jared James · Last updated 21 May 2026
Definition
The round brilliant cut is the most popular diamond shape in the world, designed specifically to maximise the brilliance, fire and scintillation of a diamond. A standard round brilliant has 57 or 58 facets arranged precisely across the crown and pavilion to reflect and refract as much light as possible back through the top of the stone. The cut was refined mathematically in the early twentieth century and remains the benchmark against which all other cuts are judged for light performance, which is why it appears on the majority of engagement rings.
Frequently asked questions
- How many facets does a round brilliant cut diamond have?
- A round brilliant cut typically has 57 or 58 facets, the extra one being a small flat facet called the culet at the bottom of the pavilion. Those facets are arranged in precise proportions across the table, crown, girdle and pavilion to optimise light return.
- Why is the round brilliant cut so popular?
- Its geometry is designed around maximising sparkle, so it outperforms most other shapes for pure brilliance and fire. It is also versatile and suits almost every setting style, from a simple solitaire to a halo or pavé band, and that combination of performance and wearability has kept it dominant for decades.
- Is a round brilliant cut diamond more expensive than other shapes?
- Generally yes, for two reasons: the demand is highest, and producing a round from rough diamond wastes more of the original stone than elongated shapes like oval or emerald cut. That combination of high demand and higher waste pushes the price per carat up compared with fancy shapes.
Designing a ring
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