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9ct Sapphire (Oval, 15.74×10.49mm, Blue) vs 12ct Diamond (Oval, 18.59×12.39mm, White)


Quick summary: When looked from above (face-up position), 12ct Diamond (18.59×12.39mm, oval cut) appears 40% larger than 9ct Sapphire (15.74×10.49mm, oval cut). See below how they compare side-by-side on a ring and finger.

9ct Sapphire (oval cut)
vs
 12ct Diamond (oval cut)
blue
 
white
15.74×10.49 mm 18.59×12.39 mm
actual size
Actual size of 9ct Sapphire (oval cut, 15.74×10.49mm, Blue color)   Actual size of 12ct Diamond (oval cut, 18.59×12.39mm, White color)
 
Actual size is set for screen
Ring: Skin tone:
Ring width: 3.0 mm
Left finger image
Ring on left finger
Blue 9ct Sapphire (oval cut, 15.74×10.49mm) on a left ring and finger
64 mm
Right finger image
Ring on a right finger
White 12ct Diamond (oval cut, 18.59×12.39mm) 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
 63% vs 74%
Saved...
Ring diameter: 16.9 mm
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Actual sizes of 9ct Sapphire Oval (15.74×10.49mm, Blue) and 12ct Diamond Oval (18.59×12.39mm, 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.


9 Ct Sapphire (Oval) 12 Ct Diamond (Oval)
15.74×10.49 mm vs 18.59×12.39 mm
135.39 mm²   188.87 mm²
Face-up size outline for 12ct Diamond (18.59×12.39mm, oval cut)
Face-up size outline for 9ct Sapphire (15.74×10.49mm, oval cut)
9ct Sapphire Oval (15.74×10.49mm)
12ct Diamond Oval (18.59×12.39mm)
Difference: 40% (53.48 mm²)
12ct Diamond (Oval, 18.59×12.39mm) has approx. 40% more face-up area than 9ct Sapphire (Oval, 15.74×10.49mm).


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