Round Cut Diamonds

According to Wikipedia, the round cut diamond is the most popular diamond shape, representing approximately 75% of all diamonds sold. 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.

Table, Depth & Other Specifications for Ideal Round Cut Diamonds

The original Tolkowsky specifications (53% table, 59.3% depth, 34.50 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 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.

round-cut

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Ideal Cut (Most Sparkle)

Excellent Cut

Very Good

Table %

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53 - 58

Sl1 - Sl2

l1

Depth %

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59 - 62.3

Sl1 - Sl2

l1

Girdle

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Thin to Slightly Thick

Thin to Slightly Thick

Sl2

Culet

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None

None

Very Small

Length to Width Ratio

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1 - 1.01

VS2 - Sl1

Sl2

Color Recommendations for Round Cut Diamonds

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. The color chart below provides a general guide for evaluating color in round diamonds.

round-cut

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Carat Weight

No Visible Color

Limited Color Okay

Prefer a Warmer Color

< 0.5

D - J

K - L

M +

0.75

D - I

J - K

L +

1

D - H

I - J

K +

1.5

D - G

H - I

J +

2.0 +

D - G

H - I

J +

Clarity Recommendations for Round Cut Diamonds

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 clarity chart below provides a general guide for evaluating clarity in round diamonds.

round-cut
round-cut

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Caret Weight

Clean Under Light Magnification

Clean to the “Naked Eye” Visible Blemish Okay

Visible Blemish Okay As Long As Not Very Obvious

< 0.5

FLV-S2

SI1-SI2

l1

0.75

FLV-S2

SI1-SI2

l1

1

FLV-S2

SI1

Sl2

1.5

FLV-S1

VS2-SI1

Sl2

2.0 +

FLV-S1

VS2-SI1

Sl2

Length to Width Ratio for Round Cut Diamonds

All round diamonds in our diamond search engine have the length and width listed. The ratio is simply the length divided by the width. This number will help you see how symmetrical the diamond is. See, the larger the length to width ratio is, the less symmetrical your round diamond. I think a round diamond should have a length to width ratio between 1.00 and 1.02!

1.30

1.40

1.45

Settings that Pair Well with Round Cut Diamonds

All round diamonds in our diamond search engine have the length and width listed. The ratio is simply the length divided by the width. This number will help you see how symmetrical the diamond is. See, the larger the length to width ratio is, the less symmetrical your round diamond. I think a round diamond should have a length to width ratio between 1.00 and 1.02!

Money Tips

When looking for a round cut diamond, make sure to always try to maximize measurements within your ideally cut diamond. For example, you can have a 1.0 carat diamond with measurements 6.36 x 6.45 mm that is ideally cut. You could also have a 0.98 carat diamond with measurements 6.45 x 6.45 mm that is just as ideally cut that is probably cheaper. The second option may be a better option.

3 Things to Ask Your Jeweler

  • 01.

    Photo & Video

    Always ask the jeweler you are buying from for a detailed picture or video like this one.

  • 02.

    Inspect It

    Ask the jeweler to pull the diamond and actually visually inspect it.

  • 03.

    Measure It

    Make sure your diamond’s measurements are maximized within your carat size.

See Our Patronus

With a Round Cut Diamond

Other Ring Resources

See our in-depth educational guides, which were made to give practical advice with every aspect of your ring.

Diamonds

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Moissanite

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Sapphires

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Gold Palladium & Platinum

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