8.5ct Princess (11.25×11.25×8.1) vs 10ct Princess (11.87×11.87×8.55)

Diamond size comparison

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Actual size of 8.5ct Princess diamond
Actual size
sample image
vs.
Actual size of 10ct Princess diamond
Actual size
sample image
8.5 ct Princess (11.25×11.25×8.1mm) 10 ct Princess (11.87×11.87×8.55mm)
Cutting style
Modified brilliant
Modified brilliant
Weight
8.5 ct
10 ct
Measurements
11.25×11.25×8.1 mm
11.87×11.87×8.55 mm
Total depth
72% OK
72% OK
L/W ratio
1
1
Face-up size
Adequate
Adequate
 
This diamond LOOKS its weight!
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 8.5ct Princess (11.25×11.25×8.1mm) and 10ct Princess (11.87×11.87×8.55mm) 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.
Settings
Ring: Skin tone:
Ring width: 3.0 mm
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Left finger image
Ring on a left finger
8.5ct Princess on a left ring
64 mm
Right finger image
Ring on a right finger
10ct Princess 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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8.5ct Princess side view Side view of ring
vs
10ct Princess side view Side view of ring
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Face-up area
126.56 mm² 
140.9 mm² 
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
8.5ct Princess (11.25×11.25×8.1mm)
10ct Princess (11.87×11.87×8.55mm)
Difference: 14.34mm² (11%)
10 carat Princess (11.87×11.87×8.55mm) has approx. 11% more face-up area than 8.5 carat Princess (11.25×11.25×8.1mm).
Face-up area per carat
14.89 mm²/ct
14.09 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. Princesses, for example, are brilliant cuts which means they mask color and inclusions quite well. If you go a bit down on the color and clarity scale, no one will know the difference, but your wallet. 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).
8.5ct Princess (11.25×11.25×8.1mm)
10ct Princess (11.87×11.87×8.55mm)
Price (best value)
Min. clarity
VS2, SI1 or better
VS2, SI1 or better
Min. color (platinum setting)
I+
I+
Min. color (yellow gold setting)
J+
J+
Depth percentage
64 - 75%
64 - 75%
Table percentage
60 - 75%
60 - 75%
Length-to-width ratio
1.00 - 1.05
1.00 - 1.05
Min. polish/symmetry
Good or better
Good or better
 Detailed buying guide

Additional Info

8.5ct Princess (11.25×11.25×8.1mm)
10ct Princess (11.87×11.87×8.55mm)
Face-up size
Normal for 8.5 carat Princess
Normal for 10 carat Princess
Facets
usually between 50 - 58
usually between 50 - 58
Length
11.25 mm
11.87 mm
Width
11.25 mm
11.87 mm
Depth
8.1 mm
8.55 mm
Gram weight
1.7 g (0.06 ounces)
2 g (0.0705 ounces)
Points
850 pts
1000 pts
Volume
482.95 mm³
568.18 mm³


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Depth percentage for 8.5 carat Princess (11.25×11.25×8.1mm)

Depth percentage of Princess cut is the ratio of the total depth (measured from table to culet) to its width. The total depth percentage of this diamond is 72%, which is OK. (Recommended depth percentage for Princesses is between 64% and 75%)

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

8.5 carat Princess (11.25×11.25×8.1mm) depth %:
Total depth: 8.1 mm
Width = 11.25 mm
Depth % = (8.1 ÷ 11.25 ) × 100 = 72%

Depth percentage for 10 carat Princess (11.87×11.87×8.55mm)

Depth percentage of Princess cut is the ratio of the total depth (measured from table to culet) to its width. The total depth percentage of this diamond is 72%, which is OK. (Recommended depth percentage for Princesses is between 64% and 75%)

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

10 carat Princess (11.87×11.87×8.55mm) depth %:
Total depth: 8.55 mm
Width = 11.87 mm
Depth % = (8.55 ÷ 11.87 ) × 100 = 72%

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 8.5 carat Princess (11.25×11.25×8.1mm)

The face-up size of this 8.5 carat Princess (11.25×11.25×8.1mm) is within the normal range for 8.5ct diamonds of this shape. Compared to 8.5ct Princess 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 8.5 carat Princess with less sparkle and the same face-up size as a well cut 8.1ct Princess, which one would you choose?

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

8.5 carat Princess reference diamond
Since there are no specific ideal proportions defined for Princess cuts, an estimation formula is used to calculate the Princess reference diamond.
Parameters:
Weight: 8.5ct
Depth: 72%
L/W ratio: 1
 
Calculated values:
Length: 11.25 mm
Width: 11.25 mm
Depth: 8.1 mm
Face-up area: 126.56 mm²
Note: Princess diamonds with face-up area of within 8% lower and 12% higher than reference Princess diamond area are considered to be of adequate face-up size.

Face-up size evaluation for 10 carat Princess (11.87×11.87×8.55mm)

The face-up size of this 10 carat Princess (11.87×11.87×8.55mm) is within the normal range for 10ct diamonds of this shape. Compared to 10ct Princess 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 10 carat Princess with less sparkle and the same face-up size as a well cut 9.5ct Princess, which one would you choose?

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

10 carat Princess reference diamond
Since there are no specific ideal proportions defined for Princess cuts, an estimation formula is used to calculate the Princess reference diamond.
Parameters:
Weight: 10ct
Depth: 72%
L/W ratio: 1
 
Calculated values:
Length: 11.87 mm
Width: 11.87 mm
Depth: 8.55 mm
Face-up area: 140.9 mm²
Note: Princess diamonds with face-up area of within 8% lower and 12% higher than reference Princess diamond area are considered to be of adequate face-up size.

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 8.5ct Princess (11.25×11.25×8.1mm):
Top surface area = 126.56 mm²
Weight = 8.5ct

Face-up area per carat = 126.56 ÷ 8.5 = 14.89mm²/ct

Face-up area per carat for 10ct Princess (11.87×11.87×8.55mm):
Top surface area = 140.9 mm²
Weight = 10ct

Face-up area per carat = 140.9 ÷ 10 = 14.09mm²/ct

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