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What is a Round Cut Diamond?

by Willyou.net * May 18, 2021

The Round Brilliant cut is the most popular cut available today. The cut is a round diamond with no sharp edges and has 58 facets. Of all diamonds, the Round cut shows the most sparkle, brilliance, and diamond bling if you look at it from above. The Round cut is such a stunning and brilliant diamond; it’s no wonder that it’s such a popular choice for brides. 

round cut diamond
Round cut diamond

Round Cut Diamond History

It was in the 17th century that the Round Brilliant cut was introduced. In the beginning, it had 17 facets on the crown (upper half), and eventually, it was increased to 33, which enhanced its fire and brilliance.
By 1900, modern diamond cutting and diamond cuts such as the round brilliant cut were made possible by the development of diamond saws and good jewelry lathes. This cut was analyzed in 1919 by Marcel Tolkowsky, whose calculations took brilliance (how much white light was reflected) and fire into consideration, creating a delicate balance between the two. Future brilliant-cut modifications, guidelines, and standards will be based on these calculations.

Choosing a Round Cut Diamond

A Round cut diamond should be set with 4 prongs or 6 prongs to protect the diamond polish and light. Round cuts work with many different styles, including solitaire and three-stone engagement rings.

For a classic Round cut, look for a length-to-width ratio of 1.00 to 1.01. A length-to-width ratio of 1.02 still looks round because the sides of the diamond will create the illusion of a greater width in the center.

The following cut, color, and clarity guides should be taken into consideration when choosing a Round cut diamond: 

Round Cut Diamond Guide – Cut

The cut attributes of a diamond contribute to its sparkle, brilliance, and bling. Most knowledgeable buyers would choose attributes from the Excellent – Very Good columns.

ExcellentVery GoodGoodFairPoor
Table %56 – 59.954 – 55.9
60 – 60.9
52 – 53.9
61 – 64.9
50 – 51.9 or
65 – 69.9
Depth %59 – 62.358 – 58.9
62.4 – 63.5
57.5 – 57.9 or
63.9 – 64.1
56.5 – 57.4 or
64.2 – 65.9
to Slightly Thick
Very Thin
to Slightly Thick
Very Thin
Very Thin
Very Thick
Extremely Thin
CuletNoneVery SmallSmallMedium>Medium

Round Cut Diamond Length-to-Width Guide

A classic Round Cut diamond has a length-to-width ratio of 1.00 to 1.01.

ExcellentVery GoodGoodFairPoor
L/W Ratio1.00 – 1.0091.01 – 1.0191.02 – 1.029 1.03 – 1.033>1.034

Round Cut Diamond Symmetry, Polish, Cut and Fluorescence Guide

Our experience suggests that Cut, Symmetry, Polish, and Fluorescence contributes to a diamond’s brilliance so that most buyers will choose Excellent – Very Good and Fluorescence None – Faint.

ExcellentVery GoodGoodFairPoor
CutExcellentVery GoodGoodFair – Poor
PolishExcellentVery GoodGoodFair – Poor
SymmetryExcellentVery GoodGoodFair – Poor
Fluorescence NoneFaintMediumStrong –
Very Strong

Round Cut Diamond Color Guide

Most buyers prefer size over color hue and will buy a diamond of G color.

ExcellentVery GoodGoodFairPoor
< 0.50 ct.D – GH – IJ – KL – M > N
0.51 – 1.00 ct.D – GH – IIJ – KK> L
1.00 – 2.00 ct.D – GHI – JK> L
>2.00 ct.D – GHI – JK> L

Round Cut Diamond Clarity Guide

Most buyers prefer size over clarity cleanse and will buy a diamond of SI1 Clarity.

ExcellentVery GoodGoodFairPoor
< 0.50 ct.FL – VS2SI1 – SI2I1I2> I3
0.51 – 1.00 ct.FL – VS1VS2 – SI1SI2I1 – I2> I3
1.00 – 2.00 ct.FL – VS1VS2 – SI1SI2I1I2 – I3
>2.00 ct.FL – VS1VS2 – SI1SI2I1I2 – I3

Advantages and Disadvantages

An advantage:
The Round cut diamond is versatile and looks beautiful in almost any engagement ring setting. When placed in intricate settings, they are just as beautiful when set on a simple band like a solitaire.

A disadvantage:
The Round cut diamond is the most expensive diamond cut. This is partly because of the high amount of diamond rough wasted with the cutting process. Due to lower yields, consumer prices rise.

Hand-Selected Round Cut Diamonds You Should See

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