6.8ct Cushion (12×12×7) vs 7ct Radiant (12×10×7)

Diamond size comparison

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Actual size of 6.8ct Cushion diamond
Actual size
sample image
vs.
Actual size of 7ct Radiant diamond
Actual size
sample image
6.8 ct Cushion (12×12×7mm) 7 ct Radiant (12×10×7mm)
Cutting style
(modified) brilliant
Mixed
Weight
6.8 ct
7 ct
Measurements
12×12×7 mm
12×10×7 mm
Total depth
58.3% too shallow!
70% OK
L/W ratio
1
1.2
Face-up size
Inadequate
Adequate
 
This diamond is a SPREAD CUT!
This diamond LOOKS its weight!
Actual diamond size
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).

Here you can see the actual sizes of 6.8ct Cushion (12×12×7mm) and 7ct Radiant (12×10×7mm) 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
6.8ct Cushion on a left ring
64 mm
Right finger image
Ring on a right finger
7ct Radiant 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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6.8ct Cushion side view Side view of ring
vs
7ct Radiant side view Side view of ring
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Face-up area
129.6 mm²  (±5%)
114 mm²  (±4%)
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
6.8ct Cushion (12×12×7mm)
7ct Radiant (12×10×7mm)
Difference: 15.6mm² (14%)
6.8 carat Cushion (12×12×7mm) has approx. 14% more face-up area than 7 carat Radiant (12×10×7mm).
Face-up area per carat
19.06 mm²/ct
16.29 mm²/ct
To learn about the accuracy of these numbers, click here.


Quick Buying Guide

Diamond prices vary greatly as they depend on the combination of unique characteristics (4Cs - Cut, Color, Clarity, and Carat). For best value, it's important to choose the combination that will reduce the price without having a negative impact on appearance.

Each shape has its own recommended balance of qualities that will give you the most bang for your buck. Below is a quick buying guide to give you an idea, but for more detailed explanation, please see the complete buying guides for the respective diamonds (links below).
6.8ct Cushion (12×12×7mm)
7ct Radiant (12×10×7mm)
Price (best value)
Min. clarity
SI1 or better
SI or better
Min. color (platinum setting)
H+
H+
Min. color (yellow gold setting)
J+
J+
Depth percentage
59 - 70%
59 - 70%
Table percentage
56 - 70%
58 - 70%
Length-to-width ratio
1.00 - 1.35
1.00 - 1.35
Min. polish/symmetry
Good or better
Good or better
 Detailed buying guide

Additional Info

6.8ct Cushion (12×12×7mm)
7ct Radiant (12×10×7mm)
Face-up size
Too large for 6.8 carat Cushion
Normal for 7 carat Radiant
Facets
usually 58
usually between 62 - 70
Length
12 mm
12 mm
Width
12 mm
10 mm
Depth
7 mm
7 mm
Gram weight
1.36 g (0.048 ounces)
1.4 g (0.0494 ounces)
Points
680 pts
700 pts
Volume
386.36 mm³
397.73 mm³


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Depth percentage for 6.8 carat Cushion (12×12×7mm)

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 58.3%, which is too shallow!. (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

6.8 carat Cushion (12×12×7mm) depth %:
Total depth: 7 mm
Width = 12 mm
Depth % = (7 ÷ 12 ) × 100 = 58.3%

Depth percentage for 7 carat Radiant (12×10×7mm)

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

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

7 carat Radiant (12×10×7mm) depth %:
Total depth: 7 mm
Width = 10 mm
Depth % = (7 ÷ 10 ) × 100 = 70%

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 6.8 carat Cushion (12×12×7mm)

The face-up size of this 6.8 carat Cushion (12×12×7mm) is out of normal range for 6.8ct diamonds of this shape. Compared to 6.8 carat Cushion reference diamond, this diamond appears too big when viewed from the top. You might think that's a good thing, however, it's not. This is a so called spread cut.

A spread cut is a diamond that is cut to maximize spread instead of optimal light performance. If compared from above, it would look larger than a well cut 6.8ct Cushion. This is not a good thing. Spread cuts are typically too shallow, which allows light to leak out of the stone resulting in less light being reflected back to the viewer's eye.

Spread cuts usually look lifeless and flat, and can sometimes exhibit a fish-eye effect. They may also come with an extremely thin girdle which can easily chip.

The bottom line: Spread cuts generally lack the brilliance and perfection that is expected of a beautiful diamond. Don't be fooled into thinking that you're getting a larger diamond for the money. This could be a rather flat, boring stone.

6.8 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: 6.8ct
Depth: 64%
L/W ratio: 1
 
Calculated values:
Length: 11.04 mm
Width: 11.04 mm
Depth: 7.07 mm
*Est. face-up area: 109.69 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 size evaluation for 7 carat Radiant (12×10×7mm)

The face-up size of this 7 carat Radiant (12×10×7mm) is within the normal range for 7ct diamonds of this shape. Compared to 7ct Radiant reference diamond (see below), this diamond is of adequate size when viewed from the top. In short, all is OK, this diamond looks its weight.

The importance of face-up size
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. Adequate size also indicates a good cut, meaning better light performance. For example, if given a choice between a poorly cut 7 carat Radiant with less sparkle and the same face-up size as a well cut 6.7ct Radiant, which one would you choose?

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

7 carat Radiant reference diamond
Since there are no specific ideal proportions defined for Radiant cuts, an estimation formula is used to calculate the Radiant reference diamond.
Parameters:
Weight: 7ct
Depth: 64%
L/W ratio: 1
 
Calculated values:
Length: 11.05 mm
Width: 11.05 mm
Depth: 7.07 mm
*Est. face-up area: 116 mm²
Note: Radiant diamonds with face-up area of within 9% lower and 12% higher than reference Radiant diamond area are considered to be of adequate face-up size.
* Estimated Face-up area: Face-up area of Radiant cuts is only an estimation (±4%). 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 6.8ct Cushion (12×12×7mm):
Top surface area = 129.6 mm²
Weight = 6.8ct

Face-up area per carat = 129.6 ÷ 6.8 = 19.06mm²/ct

Face-up area per carat for 7ct Radiant (12×10×7mm):
Top surface area = 114 mm²
Weight = 7ct

Face-up area per carat = 114 ÷ 7 = 16.29mm²/ct

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