1 Carat Round (6.5×6.5×3.92mm) vs. 1 Carat Cushion (5.83×5.83×3.73mm)

Diamond comparison

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Actual size of 1ct Round diamond
Actual size
sample image
vs.
Actual size of 1ct Cushion diamond
Actual size
sample image
1 ct Round (6.5×6.5×3.92mm) 1 ct Cushion (5.83×5.83×3.73mm)
Cutting style
Brilliant
(modified) brilliant
Weight
1 ct
1 ct
Measurements
6.5×6.5×3.92 mm
5.83×5.83×3.73 mm
Total depth
60.3% OK
64% OK
L/W ratio
1
1
Face-up size
Adequate
Adequate
 
This diamond LOOKS its weight!
This diamond LOOKS its weight!
Actual diamond size
Before purchasing a diamond, one should make sure it looks its weight. It's important to understand that carat weight does not equal face-up size.

Two diamonds of exactly the same weight (and shape) can vary quite considerably in face-up size. This depends on the proportions of the cut (e.g., deep cuts will face up smaller).

On the right you can see the actual sizes of 1ct Round (6.5×6.5×3.92mm) and 1ct Cushion (5.83×5.83×3.73mm) as they would appear on a ring and finger.

Adjust the ring and finger size to get an idea of how these stones would look on your finger. To choose different diamonds or to change diamond parameters click here.
Settings
Ring: Skin tone:
Ring width: 3.0 mm
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Left finger image
Ring on a left finger
1ct Round on a left ring
64 mm
Right finger image
Ring on a right finger
1ct Cushion on a right ring
Your settings
Ring
Gold
Skin tone
Light
Ring diameter
16.9 mm
Ring width
3.0 mm
Finger length
64 mm
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Ring diameter: 16.9 mm
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1ct Round side view Side view of ring
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1ct Cushion side view Side view of ring
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Face-up area
33.18 mm² 
30.59 mm²  (±5%)
Face-up area is a measure of the size of the diamond when viewed from the top (as set in a ring).

It tells you how big the diamond is at the girdle plane. It's important for a diamond to have sufficient face-up size for its carat weight.
Face-up size outline
Face-up size outline
1ct Round (6.5×6.5×3.92mm)
1ct Cushion (5.83×5.83×3.73mm)
Difference: 2.59mm² (8%)
1 carat Round (6.5×6.5×3.92mm) has approx. 8% more top surface area than 1 carat Cushion (5.83×5.83×3.73mm).
Face-up area per carat
33.18 mm²/ct
30.59 mm²/ct
To learn about the accuracy of these numbers, click here.

Quick Buying Guide

1ct Round (6.5×6.5×3.92mm)
1ct Cushion (5.83×5.83×3.73mm)
Min. clarity
SI or better
SI1 or better
Min. color (platinum solitaire)
J+
H+
Depth percentage
58 - 62.5%
59 - 70%
Table percentage
53 - 58%
56 - 70%
Length-to-width ratio
1.00 - 1.02
1.00 - 1.35
Min. polish/symmetry
Good or better
Good or better
 Detailed buying guide

Additional Info

1ct Round (6.5×6.5×3.92mm)
1ct Cushion (5.83×5.83×3.73mm)
Face-up size
Normal for 1 carat Round
Normal for 1 carat Cushion
Facets
58 (57 if no culet)
usually 58
Length
6.5 mm
5.83 mm
Width
6.5 mm
5.83 mm
Depth
3.92 mm
3.73 mm
Gram weight
0.2 g (0.0071 ounces)
0.2 g (0.0071 ounces)
Points
100 pts
100 pts
Volume
56.82 mm³
56.82 mm³


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Depth percentage for 1 carat Round (6.5×6.5×3.92mm)

Depth percentage of Round cut is the ratio of the total depth (measured from table to culet) to its average diameter. The total depth percentage of this diamond is 60.3%, which is OK. (Recommended depth percentage for Rounds is between 58% and 62.5%)

Depth percentage for rounds is calculated with the following formula:
Depth % = (total depth ÷ average diameter) × 100

1 carat Round (6.5×6.5×3.92mm) depth %:
Total depth: 3.92 mm
Average diameter = (6.5 + 6.5) ÷ 2 = 6.5 mm
Depth % = (3.92 ÷ 6.5 ) × 100 = 60.3%

Depth percentage for 1 carat Cushion (5.83×5.83×3.73mm)

Depth percentage of Cushion cut is the ratio of the total depth (measured from table to culet) to its width. The total depth percentage of this diamond is 64%, which is OK. (Recommended depth percentage for Cushions is between 59% and 70%)

Depth percentage for cushions is calculated with the following formula:
Depth % = (total depth ÷ width) × 100

1 carat Cushion (5.83×5.83×3.73mm) depth %:
Total depth: 3.73 mm
Width = 5.83 mm
Depth % = (3.73 ÷ 5.83 ) × 100 = 64%

About Depth Percentage
Depth percentage is one of the most important measurements as it plays a critical role in diamond's appearance. If a diamond is cut too deep or too shallow, light leaks out, making the stone less brilliant and fiery. Deep cuts also add hidden weight.

Diamonds that fall out of recommended depth range are generally less desirable and usually best to be avoided.


Face-up size evaluation for 1 carat Round (6.5×6.5×3.92mm)

The face-up size of this 1 carat Round (6.5×6.5×3.92mm) is within the normal range for 1ct diamonds of this shape. Compared to 1ct Round reference diamond (see below), this diamond is of adequate size when viewed from the top.

Diamonds are sold by weight (carats), but it's important to understand that weight doesn't equally translate into physical size, especially spread. Two diamonds of the same carat weight can vary greatly in spread, meaning that one diamond can appear larger than the other, even though they weight exactly the same.

Proper face-up size should play an important role when buying a diamond. When a diamond is set in a ring, your eyes will only see the face-up area, so you should make sure it's of adequate size. You probably don't want a 1 carat Round that looks like a poorly cut 0.85ct.

The bottom line: A diamond must look its weight. This one does.

1 carat Round reference diamond

1ct Round reference diamond is calculated from the following ideal proportions:
Proportions:
Table: 57%
Crown angle: 34°
Pavilion angle: 40.7°
Girdle: 2.8%
Star length: 50%
Lower half-length: 80%
Culet: None
 
Calculated values:
Depth: 60.3%
Crown height: 14.5%
Pavilion height: 43%
For 1 carat weight:
Diameter: 6.5 mm
Face-up area: 33.18 mm²
Note: Round diamonds with face-up area of within 5% lower and 3% higher than reference Round diamond area are considered to be of adequate face-up size.
To learn more about diamond size evaluation, click here.


Face-up size evaluation for 1 carat Cushion (5.83×5.83×3.73mm)

The face-up size of this 1 carat Cushion (5.83×5.83×3.73mm) is within the normal range for 1ct diamonds of this shape. Compared to 1ct Cushion reference diamond (see below), this diamond is of adequate size when viewed from the top.

Diamonds are sold by weight (carats), but it's important to understand that weight doesn't equally translate into physical size, especially spread. Two diamonds of the same carat weight can vary greatly in spread, meaning that one diamond can appear larger than the other, even though they weight exactly the same.

Proper face-up size should play an important role when buying a diamond. When a diamond is set in a ring, your eyes will only see the face-up area, so you should make sure it's of adequate size. You probably don't want a 1 carat Cushion that looks like a poorly cut 0.85ct.

The bottom line: A diamond must look its weight. This one does.

1 carat Cushion reference diamond

Since there are no specific ideal proportions defined for Cushion cuts, an estimation formula is used to calculate the Cushion reference diamond.
Parameters:
Weight: 1ct
Depth: 64%
L/W ratio: 1
 
Calculated values:
Length: 5.83 mm
Width: 5.83 mm
Depth: 3.73 mm
*Est. face-up area: 30.59 mm²
Note: Cushion diamonds with face-up area of within 9% lower and 12% higher than reference Cushion diamond area are considered to be of adequate face-up size.
* Estimated Face-up area: Face-up area of Cushion cuts is only an estimation (±5%). Due to uniqueness of each stone, it's impossible to accurately calculate face-up area given only a diamond's measurements.
To learn more about diamond size evaluation, click here.


Face-up Area per Carat

Face-up area per carat is calculated by dividing face-up area of the diamond with its carat weight. It tells you how many square millimeters of the top surface area a diamond is showing or would show for 1 carat weight. This can be useful when comparing stones of similar weights as it tells you how much spread per carat you will get.

Note: Face-up size does not linearly grow with carat weight, which means the heavier the stone, the smaller its face-up area per carat (e.g., 1ct stone will have higher face-up area per carat than 2ct stone).

Face-up area per carat for 1ct Round (6.5×6.5×3.92mm):
Top surface area = 33.18 mm²
Weight = 1ct

Face-up area per carat = 33.18 ÷ 1 = 33.18mm²/ct


Face-up area per carat for 1ct Cushion (5.83×5.83×3.73mm):
Top surface area = 30.59 mm²
Weight = 1ct

Face-up area per carat = 30.59 ÷ 1 = 30.59mm²/ct


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