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4ct Sapphire (Oval, 12×8mm, Dark Blue) vs 0.3ct Diamond (Round, 4.35×4.35mm, White)


Quick summary: When looked from above (face-up position), 4ct Sapphire (12×8mm, oval cut) appears 5.3 times larger than 0.3ct Diamond (4.35×4.35mm, round cut). See below how they compare side-by-side on a ring and finger.

4ct Sapphire (oval cut)
vs
 0.3ct Diamond (round cut)
dark blue
 
white
12×8 mm 4.35×4.35 mm
actual size
Actual size of 4ct Sapphire (oval cut, 12×8mm, Dark Blue color)   Actual size of 0.3ct Diamond (round cut, 4.35×4.35mm, White color)
 
Actual size is set for screen
Ring: Skin tone:
Ring width: 3.0 mm
Left finger image
Ring on left finger
Dark Blue 4ct Sapphire (oval cut, 12×8mm) on a left ring and finger
64 mm
Right finger image
Ring on a right finger
White 0.3ct Diamond (round cut, 4.35×4.35mm) 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 26%
Saved...
Ring diameter: 16.9 mm
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Actual sizes of 4ct Sapphire Oval (12×8mm, Dark Blue) and 0.3ct Diamond Round (4.35×4.35mm, 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) 0.3 Ct Diamond (Round)
12×8 mm vs 4.35×4.35 mm
78.72 mm²   14.86 mm²
Face-up size outline for 4ct Sapphire (12×8mm, oval cut)
Face-up size outline for 0.3ct Diamond (4.35×4.35mm, round cut)
4ct Sapphire Oval (12×8mm)
0.3ct Diamond Round (4.35×4.35mm)
Difference: 430% (63.86 mm²)
4ct Sapphire (Oval, 12×8mm) has approx. 430% more face-up area than 0.3ct Diamond (Round, 4.35×4.35mm). In other words, it's 5.3x larger.


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