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20ct Sapphire (Round, 16.23×16.23mm, Blue) vs 8ct Diamond (Emerald, 13.37×9.9mm, White)


Quick summary: When looked from above (face-up position), 20ct Sapphire (16.23×16.23mm, round cut) appears 68% larger than 8ct Diamond (13.37×9.9mm, emerald cut). See below how they compare side-by-side on a ring and finger.

20ct Sapphire (round cut)
vs
 8ct Diamond (emerald cut)
blue
 
white
16.23×16.23 mm 13.37×9.9 mm
actual size
Actual size of 20ct Sapphire (round cut, 16.23×16.23mm, Blue color)   Actual size of 8ct Diamond (emerald cut, 13.37×9.9mm, White color)
 
Actual size is set for screen
Ring: Skin tone:
Ring width: 3.0 mm
Left finger image
Ring on left finger
Blue 20ct Sapphire (round cut, 16.23×16.23mm) on a left ring and finger
64 mm
Right finger image
Ring on a right finger
White 8ct Diamond (emerald cut, 13.37×9.9mm) on a right ring and finger
Your settings
Ring
 Gold
Skin tone
 Light
Ring diameter
 16.9 mm
Ring width
 3.0 mm
Finger length
 64 mm
Finger coverage
 97% vs 59%
Saved...
Ring diameter: 16.9 mm
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Actual sizes of 20ct Sapphire Round (16.23×16.23mm, Blue) and 8ct Diamond Emerald (13.37×9.9mm, White) as they would appear on a ring and finger. Adjust the ring and finger size to get an idea of how these gemstones would look on your finger.

Where to buy?

For certified gemstones, high-end gemstone jewelry, and birthstone jewelry, see Blue Nile

Face-up Size

All things being equal, Sapphire will face-up smaller than Diamond for a given carat weight, because it has higher specific gravity (4 vs. 3.52 - this means it's "heavier" compared to Diamond of the same size). Face-up size also depends heavily on the proportions of the cut.

Face-up area is a measure of the size of the gem when viewed from above (as set in a ring). It tells you how big the gem is at the girdle plane.


20 Ct Sapphire (Round) 8 Ct Diamond (Emerald)
16.23×16.23 mm vs 13.37×9.9 mm
206.88 mm²   123.1 mm²
Face-up size outline for 20ct Sapphire (16.23×16.23mm, round cut)
Face-up size outline for 8ct Diamond (13.37×9.9mm, emerald cut)
20ct Sapphire Round (16.23×16.23mm)
8ct Diamond Emerald (13.37×9.9mm)
Difference: 68% (83.78 mm²)
20ct Sapphire (Round, 16.23×16.23mm) has approx. 68% more face-up area than 8ct Diamond (Emerald, 13.37×9.9mm).


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