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4ct Sapphire (Oval, 12×8mm, Blue) vs 3ct Diamond (Oval, 11.7×7.8mm, White)


Quick summary: When looked from above (face-up position), 4ct Sapphire (12×8mm, oval cut) appears 5% larger than 3ct Diamond (11.7×7.8mm, oval cut). See below how they compare side-by-side on a ring and finger.

4ct Sapphire (oval cut)
vs
 3ct Diamond (oval cut)
blue
 
white
12×8 mm 11.7×7.8 mm
actual size
Actual size of 4ct Sapphire (oval cut, 12×8mm, Blue color)   Actual size of 3ct Diamond (oval cut, 11.7×7.8mm, White color)
 
Actual size is set for screen
Ring: Skin tone:
Ring width: 3.0 mm
Left finger image
Ring on left finger
Blue 4ct Sapphire (oval cut, 12×8mm) on a left ring and finger
64 mm
Right finger image
Ring on a right finger
White 3ct Diamond (oval cut, 11.7×7.8mm) 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
 48% vs 47%
Saved...
Ring diameter: 16.9 mm
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Actual sizes of 4ct Sapphire Oval (12×8mm, Blue) and 3ct Diamond Oval (11.7×7.8mm, 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.


4 Ct Sapphire (Oval) 3 Ct Diamond (Oval)
12×8 mm vs 11.7×7.8 mm
78.72 mm²   74.83 mm²
Face-up size outline for 4ct Sapphire (12×8mm, oval cut)
Face-up size outline for 3ct Diamond (11.7×7.8mm, oval cut)
4ct Sapphire Oval (12×8mm)
3ct Diamond Oval (11.7×7.8mm)
Difference: 5% (3.89 mm²)
4ct Sapphire (Oval, 12×8mm) has approx. 5% more face-up area than 3ct Diamond (Oval, 11.7×7.8mm).


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