1.7ct Round (7.76×7.76×4.68) vs 1.5ct Radiant (8.03×5.81×3.89)

Diamond size comparison

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Actual size

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Actual size

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1.7 ct Round (7.76×7.76×4.68mm)

1.5 ct Radiant (8.03×5.81×3.89mm)

Price

check here »

Cutting style

Brilliant

Mixed

Weight

1.7 ct

1.5 ct

Measurements

7.76×7.76×4.68 mm

8.03×5.81×3.89 mm

Total depth

60.3% → OK

67% → OK

L/W ratio

1.38

Face-up size

Adequate

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).

Here you can see the actual sizes of 1.7ct Round (7.76×7.76×4.68mm) and 1.5ct Radiant (8.03×5.81×3.89mm) 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.

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Settings

Ring:

Gold
Platinum

Skin tone:

Pale
Light
Medium
Dark

Ring width: 3.0 mm

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64 mm

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

USA	UK	Asia	EU1	EU2

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Face-up area

47.29 mm²

44.32 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.

1.7ct Round (7.76×7.76×4.68mm)
1.5ct Radiant (8.03×5.81×3.89mm)
	Difference: 2.97mm² (7%)

1.7 carat Round (7.76×7.76×4.68mm) has approx. 7% more face-up area than 1.5 carat Radiant (8.03×5.81×3.89mm).

Face-up area per carat

27.82 mm²/ct

29.55 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).

1.7ct Round (7.76×7.76×4.68mm)

1.5ct Radiant (8.03×5.81×3.89mm)

Price (best value)

check here »

Min. clarity

SI or better

Min. color (platinum setting)

J+

H+

Min. color (yellow gold setting)

K+

J+

Depth percentage

58 - 62.5%

59 - 70%

Table percentage

53 - 58%

58 - 70%

Length-to-width ratio

1.00 - 1.02

1.00 - 1.35

Min. polish/symmetry

Good or better

Detailed buying guide

Complete guide »

Additional Info

1.7ct Round (7.76×7.76×4.68mm)

1.5ct Radiant (8.03×5.81×3.89mm)

Face-up size

Normal for 1.7 carat Round

Normal for 1.5 carat Radiant

Facets

58 (57 if no culet)

usually between 62 - 70

Length

7.76 mm

8.03 mm

Width

7.76 mm

5.81 mm

Depth

4.68 mm

3.89 mm

Gram weight

0.34 g (0.012 ounces)

0.3 g (0.0106 ounces)

Points

170 pts

150 pts

Volume

96.59 mm³

85.23 mm³

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Depth percentage for 1.7 carat Round (7.76×7.76×4.68mm)

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

1.7 carat Round (7.76×7.76×4.68mm) depth %:

Total depth: 4.68 mm
Average diameter = (7.76 + 7.76) ÷ 2 = 7.76 mm

Depth % = (4.68 ÷ 7.76 ) × 100 = 60.3%

Depth percentage for 1.5 carat Radiant (8.03×5.81×3.89mm)

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 67%, 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

1.5 carat Radiant (8.03×5.81×3.89mm) depth %:

Total depth: 3.89 mm
Width = 5.81 mm

Depth % = (3.89 ÷ 5.81 ) × 100 = 67%

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 1.7 carat Round (7.76×7.76×4.68mm)

The face-up size of this 1.7 carat Round (7.76×7.76×4.68mm) is within the normal range for 1.7ct diamonds of this shape. Compared to 1.7ct Round 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. Would you want a poorly cut 1.7 carat diamond that is less sparkly and has the same face-up size as an ideal cut 1.5 carat? Probably not.

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

1.7 carat Round reference diamond

1.7ct 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 1.7 carat weight:
Diameter:	7.76 mm
Face-up area:	47.29 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 1.5 carat Radiant (8.03×5.81×3.89mm)

The face-up size of this 1.5 carat Radiant (8.03×5.81×3.89mm) is within the normal range for 1.5ct diamonds of this shape. Compared to 1.5ct 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 1.5 carat Radiant with less sparkle and the same face-up size as a well cut 1.4ct Radiant, which one would you choose?

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

1.5 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:	1.5ct
Depth:	64%
L/W ratio:	1

Calculated values:
Length:	6.61 mm
Width:	6.61 mm
Depth:	4.23 mm
*Est. face-up area:	41.51 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 1.7ct Round (7.76×7.76×4.68mm):

Top surface area = 47.29 mm²
Weight = 1.7ct

Face-up area per carat = 47.29 ÷ 1.7 = 27.82mm²/ct

Face-up area per carat for 1.5ct Radiant (8.03×5.81×3.89mm):

Top surface area = 44.32 mm²
Weight = 1.5ct

Face-up area per carat = 44.32 ÷ 1.5 = 29.55mm²/ct

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