1.5ct Oval (8×6×3.66) vs 1.8ct Oval (9×6×3.66)

Diamond size comparison

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Actual size of 1.5ct Oval diamond
Actual size
sample image
vs.
Actual size of 1.8ct Oval diamond
Actual size
sample image
1.5 ct Oval (8×6×3.66mm) 1.8 ct Oval (9×6×3.66mm)
Cutting style
Modified brilliant
Modified brilliant
Weight
1.5 ct
1.8 ct
Measurements
8×6×3.66 mm
9×6×3.66 mm
Total depth
61% OK
61% OK
L/W ratio
1.33
1.5
Face-up size
Inadequate
Inadequate
 
This diamond does NOT look its weight!
This diamond does NOT look 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 1.5ct Oval (8×6×3.66mm) and 1.8ct Oval (9×6×3.66mm) 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
1.5ct Oval on a left ring
64 mm
Right finger image
Ring on a right finger
1.8ct Oval 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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1.5ct Oval side view Side view of ring
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1.8ct Oval side view Side view of ring
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Face-up area
39.36 mm²  (±5%)
44.28 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
1.5ct Oval (8×6×3.66mm)
1.8ct Oval (9×6×3.66mm)
Difference: 4.92mm² (13%)
1.8 carat Oval (9×6×3.66mm) has approx. 13% more face-up area than 1.5 carat Oval (8×6×3.66mm).
Face-up area per carat
26.24 mm²/ct
24.6 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).
1.5ct Oval (8×6×3.66mm)
1.8ct Oval (9×6×3.66mm)
Price (best value)
Min. clarity
SI or better
SI or better
Min. color (platinum setting)
I+
I+
Min. color (yellow gold setting)
J+
J+
Depth percentage
59 - 65%
59 - 65%
Table percentage
53 - 62%
53 - 62%
Length-to-width ratio
1.25 - 1.65
1.25 - 1.65
Min. polish/symmetry
Good or better
Good or better
 Detailed buying guide

Additional Info

1.5ct Oval (8×6×3.66mm)
1.8ct Oval (9×6×3.66mm)
Face-up size
Too small for 1.5 carat Oval
Too small for 1.8 carat Oval
Facets
usually 58
usually 58
Length
8 mm
9 mm
Width
6 mm
6 mm
Depth
3.66 mm
3.66 mm
Gram weight
0.3 g (0.0106 ounces)
0.36 g (0.0127 ounces)
Points
150 pts
180 pts
Volume
85.23 mm³
102.27 mm³


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Depth percentage for 1.5 carat Oval (8×6×3.66mm)

Depth percentage of Oval cut is the ratio of the total depth (measured from table to culet) to its width. The total depth percentage of this diamond is 61%, which is OK. (Recommended depth percentage for Ovals is between 59% and 65%)

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

1.5 carat Oval (8×6×3.66mm) depth %:
Total depth: 3.66 mm
Width = 6 mm
Depth % = (3.66 ÷ 6 ) × 100 = 61%

Depth percentage for 1.8 carat Oval (9×6×3.66mm)

Depth percentage of Oval cut is the ratio of the total depth (measured from table to culet) to its width. The total depth percentage of this diamond is 61%, which is OK. (Recommended depth percentage for Ovals is between 59% and 65%)

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

1.8 carat Oval (9×6×3.66mm) depth %:
Total depth: 3.66 mm
Width = 6 mm
Depth % = (3.66 ÷ 6 ) × 100 = 61%

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 1.5 carat Oval (8×6×3.66mm)

The face-up size of this 1.5 carat Oval (8×6×3.66mm) is out of normal range for 1.5ct diamonds of this shape. Compared to 1.5 carat Oval reference diamond, this diamond appears too small when viewed from the top, which makes it a chubby.

A chubby is a diamond with hidden extra weight that looks smaller than it should when viewed from the top. Hidden weight is typically a result of a poor cut usually linked to oversized girdle, deeper pavilion, and/or steeper crown.

In order to maximize profits, diamond cutters tend to retain as much weight from the rough as possible. This practice, however, can have detrimental effects on the stone's face-up size and its optical qualities. Poorly proportioned stones look duller and sparkle less than well cut stones. Chubby stones also look smaller.

The bottom line: One should never sacrifice beauty for weight. You probably don't want to pay for extra weight that doesn't add anything to the beauty. You want a stone that looks its weight. This 1.5ct Oval doesn't - from above, its size is comparable to a well cut 1.11ct Oval.

1.5 carat Oval reference diamond
Since there are no specific ideal proportions defined for Oval cuts, an estimation formula is used to calculate the Oval reference diamond.
Parameters:
Weight: 1.5ct
Depth: 61%
L/W ratio: 1.5
 
Calculated values:
Length: 9.39 mm
Width: 6.26 mm
Depth: 3.82 mm
*Est. face-up area: 48.2 mm²
Note: Oval diamonds with face-up area of within 9% lower and 12% higher than reference Oval diamond area are considered to be of adequate face-up size.
* Estimated Face-up area: Face-up area of Oval 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.

Face-up size evaluation for 1.8 carat Oval (9×6×3.66mm)

The face-up size of this 1.8 carat Oval (9×6×3.66mm) is out of normal range for 1.8ct diamonds of this shape. Compared to 1.8 carat Oval reference diamond, this diamond appears too small when viewed from the top, which makes it a chubby.

A chubby is a diamond with hidden extra weight that looks smaller than it should when viewed from the top. Hidden weight is typically a result of a poor cut usually linked to oversized girdle, deeper pavilion, and/or steeper crown.

In order to maximize profits, diamond cutters tend to retain as much weight from the rough as possible. This practice, however, can have detrimental effects on the stone's face-up size and its optical qualities. Poorly proportioned stones look duller and sparkle less than well cut stones. Chubby stones also look smaller.

The bottom line: One should never sacrifice beauty for weight. You probably don't want to pay for extra weight that doesn't add anything to the beauty. You want a stone that looks its weight. This 1.8ct Oval doesn't - from above, its size is comparable to a well cut 1.36ct Oval.

1.8 carat Oval reference diamond
Since there are no specific ideal proportions defined for Oval cuts, an estimation formula is used to calculate the Oval reference diamond.
Parameters:
Weight: 1.8ct
Depth: 61%
L/W ratio: 1.5
 
Calculated values:
Length: 9.87 mm
Width: 6.58 mm
Depth: 4.01 mm
*Est. face-up area: 53.25 mm²
Note: Oval diamonds with face-up area of within 9% lower and 12% higher than reference Oval diamond area are considered to be of adequate face-up size.
* Estimated Face-up area: Face-up area of Oval 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.

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 1.5ct Oval (8×6×3.66mm):
Top surface area = 39.36 mm²
Weight = 1.5ct

Face-up area per carat = 39.36 ÷ 1.5 = 26.24mm²/ct

Face-up area per carat for 1.8ct Oval (9×6×3.66mm):
Top surface area = 44.28 mm²
Weight = 1.8ct

Face-up area per carat = 44.28 ÷ 1.8 = 24.6mm²/ct

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