0.25ct Trillion (4.87×4.87×1.95) vs 0.5ct Round (5×5×2.9)

Diamond size comparison

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Actual size of 0.25ct Trillion diamond
Actual size
sample image
Actual size of 0.5ct Round diamond
Actual size
sample image
0.25 ct Trillion (4.87×4.87×1.95mm) 0.5 ct Round (5×5×2.9mm)
Cutting style
Modified brilliant
0.25 ct
0.5 ct
4.87×4.87×1.95 mm
5×5×2.9 mm
Total depth
40% OK
58% OK
L/W ratio
Face-up size
This diamond LOOKS its weight!
This diamond BARELY 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 0.25ct Trillion (4.87×4.87×1.95mm) and 0.5ct Round (5×5×2.9mm) 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.
Ring: Skin tone:
Ring width: 3.0 mm
Left finger image
Ring on a left finger
0.25ct Trillion on a left ring
64 mm
Right finger image
Ring on a right finger
0.5ct Round on a right ring
Your settings
Skin tone
Ring diameter
16.9 mm
Ring width
3.0 mm
Finger length
64 mm
Ring diameter: 16.9 mm
0.25ct Trillion side view Side view of ring
0.5ct Round side view Side view of ring
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Face-up area
14.7 mm²  (±9%)
19.63 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
0.25ct Trillion (4.87×4.87×1.95mm)
0.5ct Round (5×5×2.9mm)
Difference: 4.93mm² (34%)
0.5 carat Round (5×5×2.9mm) has approx. 34% more face-up area than 0.25 carat Trillion (4.87×4.87×1.95mm).
Face-up area per carat
58.8 mm²/ct
39.26 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).
0.25ct Trillion (4.87×4.87×1.95mm)
0.5ct Round (5×5×2.9mm)
Price (best value)
Min. clarity
SI or better
SI or better
Min. color (platinum setting)
Min. color (yellow gold setting)
Depth percentage
32 - 48%
58 - 62.5%
Table percentage
50 - 70%
53 - 58%
Length-to-width ratio
1.00 - 1.10
1.00 - 1.02
Min. polish/symmetry
Good or better
Good or better
 Detailed buying guide

Additional Info

0.25ct Trillion (4.87×4.87×1.95mm)
0.5ct Round (5×5×2.9mm)
Face-up size
Normal for 0.25 carat Trillion
A bit small for 0.5 carat Round
Between 31 - 50
58 (57 if no culet)
4.87 mm
5 mm
4.87 mm
5 mm
1.95 mm
2.9 mm
Gram weight
0.05 g (0.0018 ounces)
0.1 g (0.0035 ounces)
25 pts
50 pts
14.2 mm³
28.41 mm³

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Depth percentage for 0.25 carat Trillion (4.87×4.87×1.95mm)

Depth percentage of Trillion cut is the ratio of the total depth (measured from table to culet) to its width. The total depth percentage of this diamond is 40%, which is OK. (Recommended depth percentage for Trillions is between 32% and 48%)

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

0.25 carat Trillion (4.87×4.87×1.95mm) depth %:
Total depth: 1.95 mm
Width = 4.87 mm
Depth % = (1.95 ÷ 4.87 ) × 100 = 40%

Depth percentage for 0.5 carat Round (5×5×2.9mm)

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 58%, 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

0.5 carat Round (5×5×2.9mm) depth %:
Total depth: 2.9 mm
Average diameter = (5 + 5) ÷ 2 = 5 mm
Depth % = (2.9 ÷ 5 ) × 100 = 58%

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 0.25 carat Trillion (4.87×4.87×1.95mm)

The face-up size of this 0.25 carat Trillion (4.87×4.87×1.95mm) is within the normal range for 0.25ct diamonds of this shape. Compared to 0.25ct Trillion 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. You probably wouldn't want a poorly cut 0.25ct Trillion that is less sparkly and faces up the same as a well-cut Trillion of a smaller weight.

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

0.25 carat Trillion reference diamond
Since there are no specific ideal proportions defined for Trillion cuts, an estimation formula is used to calculate the Trillion reference diamond.
Weight: 0.25ct
Depth: 40%
L/W ratio: 1
Calculated values:
Length: 4.87 mm
Width: 4.87 mm
Depth: 1.95 mm
*Est. face-up area: 14.7 mm²
Note: Trillion diamonds with face-up area of within 13% lower and 16% higher than reference Trillion diamond area are considered to be of adequate face-up size.
* Estimated Face-up area: Face-up area of Trillion cuts is only an estimation (±9%). 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 0.5 carat Round (5×5×2.9mm)

The face-up size of this 0.5 carat Round (5×5×2.9mm) is slightly out of normal range for 0.5ct diamonds of this shape. A well cut 0.5ct Round should have an average diameter between 5.03 and 5.24 mm. Compared to 0.5 carat Round reference diamond, this diamond appears a bit too small when viewed from the top, which means it's probably a borderline 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 0.5ct diamond has a face-up size of a well cut 0.46 carat.

0.5 carat Round reference diamond
0.5ct Round reference diamond is calculated from the following ideal 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 0.5 carat weight:
Diameter: 5.16 mm
Face-up area: 20.91 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 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 0.25ct Trillion (4.87×4.87×1.95mm):
Top surface area = 14.7 mm²
Weight = 0.25ct

Face-up area per carat = 14.7 ÷ 0.25 = 58.8mm²/ct

Face-up area per carat for 0.5ct Round (5×5×2.9mm):
Top surface area = 19.63 mm²
Weight = 0.5ct

Face-up area per carat = 19.63 ÷ 0.5 = 39.26mm²/ct

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