Round cut diamond.
The most popular diamond shape is the round brilliant cut. Carefully refined over nearly 100 years to maximize light return and sparkle, this shape has proven the test of time as a sought after choice. Almost three quarters of all diamond engagement rings feature a round brilliant diamond. Due to the mechanics of its shape, the round diamond is generally superior to fancy diamond shapes at the proper reflection of light, maximizing potential brightness. Virtually all round diamonds are brilliant cut, meaning they have 58 facets (57 when there is no culet).
Round cut diamond.
Clean, classic, versatile and with more fire and brilliance than any other shape, it would be difficult to persuade anyone against this choice, as proven by the fact that it accounts for more than half of all diamonds sold today. For men wishing to surprise their ladies and unsure of what they might like, one could hardly go wrong here.
Round cut diamond ring.
Round cut diamond features.
The round brilliant cut is the most popular diamond shape, accounting for more than half of all diamonds sold today. Although developed in Europe, the round brilliant is sometimes referred to as the American Ideal Cut.
With 58 facets divided amongst its crown, girdle and pavilion and a typical ratio between 1.00 and 1.02, it yields maximum shine as the cut naturally follows the rough diamond crystal.
The round brilliant is the most researched cut in the industry; for over a century, diamond cutters have used advanced scientific theories of light reflection and precise mathematical calculations to optimize its fire and brilliance.
The round brilliant is the most versatile of all cuts both in terms of style and value. With more fire and brilliance than any other shape, this offers the ideal balance between cut, color and clarity grades and budget.
For a bachelor unsure of what might please his lady, it is hard to go wrong with this classic choice.
Round diamonds cost more on a per carat basis than fancy shapes for two reasons; the demand for round diamonds is very high, and the yield is relatively low. Because more of the rough diamond is lost in the cutting of a round diamond, the cost of each carat retained is higher. A typical round diamond (for example; a 1.00 carat, F color, VS2 clarity, Excellent cut) may cost 25-35% more than a similar fancy shape.
The round diamond began to rise in popularity in 1919 with the publication of Marcel Tolkowsky's thesis "Diamond Design: A Study of the Reflection and Refraction of Light in Diamond". Tolkowsky's work described the ideal proportions of a round cut diamond for maximizing light return (or brilliance) and dispersion (or fire). The original Tolkowsky specifications (53% table, 59.3% depth, 34.50 degree crown angle, visible culet) have since been modified as the cut mechanics for round diamonds have perfected over time. These theoretical advancements, as well as advancements in technology (such as the use of lasers in diamond cutting), have been adopted by diamond manufacturers to produce the incredibly brilliant cuts we see today in well cut round diamonds.
The pavilion depth and angle are also significant for maximum radiance and scintillation. The pavilion is the cone-shaped part of the diamond from girdle to base. The depth percentage of the pavilion is calculated as the percentage of the pavilion depth relative to the girdle diameter. The pavilion has main facets and lower half facets that reflect fiery sparkles of light when cut to ideal proportions. A shallow pavilion angle can result in a "fish eye" effect, while a pavilion angle that is too steep can result in your diamond looking like a "nail head", with a dark centre.
Poorly cut diamonds with "nail head" and "fish eye" defects:
Poorly cut diamonds with "nail head" and "fish eye" defects.
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.
As mentioned, an excellent cut diamond may cost up to 35% more than any other diamond shape with similar characteristics.
The table below serves as a general guideline for evaluating the cut of a round diamond. GIA takes these and other factors into consideration when assigning a cut grade:
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| Round Cut Diamond | Excellent | Very Good | Good | Fair | Poor |
|---|---|---|---|---|---|
| 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 | |
| 53 - 58 | 52 - 53 or 58 - 60 | 51 or 61 - 64 | 50 or 65 - 69 | <50 or >69 | |
| Very good to excellent | Good to excellent | Good to excellent | Fair to Excellent | Poor to Excellent | |
| Very good to excellent | Good to excellent | Good to excellent | Fair to Excellent | Poor to Excellent | |
| 34 - 34.9 | 32.1 - 33.9 or 35 - 35.5 | 30.1 - 32 or 36 - 37.9 | 29 - 30 or 38 - 40.5 | <29 or >40.5 | |
| 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 | |
| Thin - Slightly Thick | Very Thin - Slightly Thick | Very Thin - Thick | Very Thin - Very Thick | Ex. Thin - Ex. Thick | |
| None | Very Small | Small | Medium | > Medium | |
| 1.00 - 1.01 | 1.00 - 1.01 | 1.00 - 1.01 | 1.02 | > 1.02 |
Round diamond cut guide
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Round diamond cut.
Round diamond length to width ratio.
Evaluating color in round cut diamonds is subjective. Keep in mind that many customers may actually prefer the ever so slightly warmer colors of a G-H diamond over the cool colorlessness of a D-F diamond. In fact, most of the premium in price associated with round diamonds at the higher end of the color scale is driven by supply and demand; customers want the D-F color grades, and are willing to pay a premium to get them. In a world without diamond color grading, the price premium for higher grades would be much lower, as the actual differences in color are difficult to perceive.
Since round cut diamonds reflect more light than any other diamond shape. they tend to mask yellowish tints in a diamond. 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 color chart below provides a general guide for evaluating color in round diamonds:
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| Round Cut Diamond | 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 | I - J | K - L | > L |
| > 2.0 ct. | D - F | G | H | I - J | > J |
| None | Faint - Med | Strong | Very Strong | Very Strong |
Round diamond color guide.
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Round cut diamond color.
Like color, evaluating clarity in round diamonds is subjective. GIA provides excellent help with their clarity grades. Still, it is important to understand that each customer will have a unique standard for clarity. Some may be perfectly comfortable with an inclusion as long as they cannot easily see it. Others may insist on a more technically flawless appearance.
The GIA grades clarity of round cut diamonds on a scale from FL to I3, where FL means a flawless diamond 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 diamonds, be ready to pay a premium price. The clarity chart below provides a general guide for evaluating clarity in round diamonds:
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| Round Cut Diamond | 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 diamond clarity guide.
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Round cut diamond clarity.
The origins of the round brilliant cut can be traced back to the middle of the 17th century when diamond cutters began using more refined and complex ways of cutting diamonds. The early brilliant cuts were known as Mazarins, after their designer Cardinal Mazarin, who made the first cross-cut diamond in 1650.
Through a series of gradual transformations and developments over the course of the 18th century, the Mazarins gave birth to the Portuguese Peruzzi, "old mine," or "old European cut" in the 1700s.
It was not until 1919 that the early modern round brilliant was created; at the time it was referred to as the Tolkowsky cut named after its creator, Russian mathematician and diamond enthusiast Marcel Tolkowsky.
Round cut diamond history.
Learn more about what you need to know in our ultimate buying guide, if you're thinking of buying a round cut diamond. We break it all down from pricing, other shapes comparison and engagement ring setting choices.
