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1ct Sapphire (Marquise, 10×4.5mm, Blue) vs 0.3ct Diamond (Round, 4.5×4.5mm, White)


Quick summary: When looked from above (face-up position), 1ct Sapphire (10×4.5mm, marquise cut) appears 2 times larger than 0.3ct Diamond (4.5×4.5mm, round cut). See below how they compare side-by-side on a ring and finger.

1ct Sapphire (marquise cut)
vs
 0.3ct Diamond (round cut)
blue
 
white
10×4.5 mm 4.5×4.5 mm
actual size
Actual size of 1ct Sapphire (marquise cut, 10×4.5mm, Blue color)   Actual size of 0.3ct Diamond (round cut, 4.5×4.5mm, White color)
 
Actual size is set for screen
Ring: Skin tone:
Ring width: 3.0 mm
Left finger image
Ring on left finger
Blue 1ct Sapphire (marquise cut, 10×4.5mm) on a left ring and finger
64 mm
Right finger image
Ring on a right finger
White 0.3ct Diamond (round cut, 4.5×4.5mm) 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
 27% vs 27%
Saved...
Ring diameter: 16.9 mm
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Actual sizes of 1ct Sapphire Marquise (10×4.5mm, Blue) and 0.3ct Diamond Round (4.5×4.5mm, 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.


1 Ct Sapphire (Marquise) 0.3 Ct Diamond (Round)
10×4.5 mm vs 4.5×4.5 mm
31.95 mm²   15.9 mm²
Face-up size outline for 1ct Sapphire (10×4.5mm, marquise cut)
Face-up size outline for 0.3ct Diamond (4.5×4.5mm, round cut)
1ct Sapphire Marquise (10×4.5mm)
0.3ct Diamond Round (4.5×4.5mm)
Difference: 101% (16.05 mm²)
1ct Sapphire (Marquise, 10×4.5mm) has approx. 101% more face-up area than 0.3ct Diamond (Round, 4.5×4.5mm). In other words, it's 2.01x larger.


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