Round is the world’s most popular diamond shape. Round cut diamonds represent more than 73% of all diamonds sold globally. If you are interested in buying a diamond that has unsurpassed brilliance and sparkle, our round cut diamond guide is a must-read.
History of Round Cut Diamonds
The history of the round cut, also referred to as the round brilliant cut, traces back to the middle of the 17th century when diamond cutters began using more refined and complex techniques.
The early brilliant cut, also known as Mazarin cut, after Cardinal Mazarin, was created in 1650. Through gradual transformations and developments, this cut gave birth to such unique cuts as Peruzzi, old mine and old European cut in the early 18th century.
The modern round brilliant cut was created by a Russian mathematician and diamond enthusiast Marcel Tolkowsky in 1919. This cut is also sometimes referred to as the Tolkowsky cut, after its creator. It features 58 or 57 facets if the culet is pointed. Since then the round cut remained the most popular diamond cut in the world.
Round Cut Diamond Cut Quality Guide
The quality of the cut is the most important factor in maximizing the brilliance and fire, meaning it greatly affects the appearance of a diamond.
According to the GIA, round brilliant diamond cut quality is graded on a scale from Excellent to Poor. The closer a diamond to excellent cut parameters, the more brilliance and sparkle it exhibits.
An excellent cut diamond may cost up to 35% more than any other diamond shape with similar characteristics.
To help you evaluate the cut of round diamonds use the table below as a general guideline.
| EXCELLENT | VERY GOOD | GOOD | FAIR | POOR | |
|---|---|---|---|---|---|
| TABLE % | 53 - 58 | 52 - 53 or 58 - 60 | 51 or 61 - 64 | 50 or 65 - 69 | < 50 or > 69 |
| DEPTH % | 59 - 62.3 | 58 - 58.9 or 62.4 - 63.5 | 57.5 - 57.9 or 63.6 - 64.1 | 56.5 - 57.4 or 64.2 - 65 | < 56.5 or > 65 |
| CROWN ANGLE | 34 - 34.9 | 32.1 - 33.9 or 35 - 35.9 | 30.1 - 32 or 36 - 37.9 | 29 - 30 or 38 - 40.5 | < 29 or > 40.5 |
| PAVILION DEPTH | 42.8 - 43.2 | 42 - 42.7 or 43.3 - 43.9 | 41 - 41.9 or 44 - 45.5 | 39 - 40.9 or 45.6 - 48 | < 39 or > 48 |
| GIRDLE | Thin to Slightly Thick | Very Thin to Slightly Thick | Very Thin to Thick | Very Thin to Very Thick | Extremely Thin to Extremely Thick |
| CULET | None | Very Small | Small | Medium | > Medium |
| LENGTH TO WIDTH RATIO | 1.00 - 1.01 | 1.00 - 1.01 | 1.00 - 1.01 | 1.02 | > 1.02 |
Round Cut Diamond Colour Guide
Colour of round diamonds is graded on a scale from D to Z, where D signifies a completely colourless stone and Z means an easily noticeable yellow or brown tint.
Since round cut diamonds reflect more light than any other diamond shape, they tend to mask yellowish tints in a stone. That is why evaluating colour in a round cut diamond is quite subjective. Some people may prefer slightly warmer colours such as G-H while others buy only colourless D-F diamonds.
The colour chart below provides a general guide for evaluating colour in round cut diamonds.
| SIZE | EXCELLENT | VERY GOOD | GOOD | FAIR | POOR |
|---|---|---|---|---|---|
| < .50 ct. | D - G | H - I | J - K | L - M | > M |
| .51-1.0 ct. | D - G | H - I | J - K | L - M | > M |
| 1.0-2.0 ct. | D - F | G - H | H | K - L | > L |
| > 2.0 ct. | D - F | G | H | I - J | > J |
Round Cut Diamond Clarity Guide
The GIA grades clarity of round cut diamonds on a scale from IF to I3, where IF means a flawless stone and I3 indicates a heavily included diamond.
For round cut diamonds, like for any other shape, the most important is to determine if the gemstone is eye clean. In other words, you should feel comfortable to buy a diamond which inclusions are not visible without magnification. In case you still prefer flawless stones, be ready to pay a premium price.
The clarity chart below provides a general guide based on the GIA clarity grading standards.
| SIZE | EXCELLENT | VERY GOOD | GOOD | FAIR | POOR |
|---|---|---|---|---|---|
| < .50 ct. | FL - VS2 | SI1 - SI2 | I1 | I2 | > I2 |
| .51-1.0 ct. | FL - VS1 | VS2 - SI1 | SI2 | I1 - I2 | > I2 |
| 1.0-2.0 ct. | FL - VVS2 | VS1 - VS2 | SI1 - SI2 | I1 | > I1 |
| > 2.0 ct. | FL - VVS2 | VS1 - VS2 | SI1 | SI2 | > SI2 |
Round Cut Diamond Price
The round brilliant cut is the most expensive diamond shape.
One of the reasons for this is that the yield is relatively high as more of the rough stone is lost while cutting a round diamond. Only 40% of the original rough remains at the end of the cutting and polishing process.
The other reason is the extremely high popularity and demand for round diamonds. Approximately 60% of all engagement rings sold yearly are made with round cut diamonds. The higher the demand, the higher the price.
And the last but not the least, the unparalleled brilliance and sparkle of this cut warrants a higher price. Round diamonds have always been among the top choices due to their classic appeal and versatile shape.
Cover image credit: Sotheby’s
