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0.25ct Sapphire (Cabochon, 4.31×2.87mm, Blue) vs 1ct Diamond (Round, 6.5×6.5mm, White)


Quick summary: When looked from above (face-up position), 1ct Diamond (6.5×6.5mm, round cut) appears 3.3 times larger than 0.25ct Sapphire (4.31×2.87mm, cabochon cut). See below how they compare side-by-side on a ring and finger.

0.25ct Sapphire (cabochon cut)
vs
 1ct Diamond (round cut)
blue
 
white
4.31×2.87 mm 6.5×6.5 mm
actual size
Actual size of 0.25ct Sapphire (cabochon cut, 4.31×2.87mm, Blue color)   Actual size of 1ct Diamond (round cut, 6.5×6.5mm, White color)
 
Actual size is set for screen
Ring: Skin tone:
Ring width: 3.0 mm
Left finger image
Ring on left finger
Blue 0.25ct Sapphire (cabochon cut, 4.31×2.87mm) on a left ring and finger
64 mm
Right finger image
Ring on a right finger
White 1ct Diamond (round cut, 6.5×6.5mm) 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
 17% vs 39%
Saved...
Ring diameter: 16.9 mm
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Actual sizes of 0.25ct Sapphire Cabochon (4.31×2.87mm, Blue) and 1ct Diamond Round (6.5×6.5mm, 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.


0.25 Ct Sapphire (Cabochon) 1 Ct Diamond (Round)
4.31×2.87 mm vs 6.5×6.5 mm
10.14 mm²   33.18 mm²
Face-up size outline for 1ct Diamond (6.5×6.5mm, round cut)
Face-up size outline for 0.25ct Sapphire (4.31×2.87mm, cabochon cut)
0.25ct Sapphire Cabochon (4.31×2.87mm)
1ct Diamond Round (6.5×6.5mm)
Difference: 227% (23.04 mm²)
1ct Diamond (Round, 6.5×6.5mm) has approx. 227% more face-up area than 0.25ct Sapphire (Cabochon, 4.31×2.87mm). In other words, it's 3.27x larger.


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