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0.3ct Sapphire (Round, 4×4mm, Purple) vs 0.42ct Diamond (Round, 4.87×4.87mm, White)


Quick summary: When looked from above (face-up position), 0.42ct Diamond (4.87×4.87mm, round cut) appears 48% larger than 0.3ct Sapphire (4×4mm, round cut). See below how they compare side-by-side on a ring and finger.

0.3ct Sapphire (round cut)
vs
 0.42ct Diamond (round cut)
purple
 
white
4×4 mm 4.87×4.87 mm
actual size
Actual size of 0.3ct Sapphire (round cut, 4×4mm, Purple color)   Actual size of 0.42ct Diamond (round cut, 4.87×4.87mm, White color)
 
Actual size is set for screen
Ring: Skin tone:
Ring width: 3.0 mm
Left finger image
Ring on left finger
Purple 0.3ct Sapphire (round cut, 4×4mm) on a left ring and finger
64 mm
Right finger image
Ring on a right finger
White 0.42ct Diamond (round cut, 4.87×4.87mm) 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
 24% vs 29%
Saved...
Ring diameter: 16.9 mm
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Actual sizes of 0.3ct Sapphire Round (4×4mm, Purple) and 0.42ct Diamond Round (4.87×4.87mm, 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.


0.3 Ct Sapphire (Round) 0.42 Ct Diamond (Round)
4×4 mm vs 4.87×4.87 mm
12.57 mm²   18.63 mm²
Face-up size outline for 0.42ct Diamond (4.87×4.87mm, round cut)
Face-up size outline for 0.3ct Sapphire (4×4mm, round cut)
0.3ct Sapphire Round (4×4mm)
0.42ct Diamond Round (4.87×4.87mm)
Difference: 48% (6.06 mm²)
0.42ct Diamond (Round, 4.87×4.87mm) has approx. 48% more face-up area than 0.3ct Sapphire (Round, 4×4mm).


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