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40ct Topaz (Round, 21.32×21.32mm, Blue) vs 38ct Ruby (Round, 20.1×20.1mm, Red)


Quick summary: When looked from above (face-up position), 40ct Topaz (21.32×21.32mm, round cut) appears 13% larger than 38ct Ruby (20.1×20.1mm, round cut). See below how they compare side-by-side on a ring and finger.

40ct Topaz (round cut)
vs
 38ct Ruby (round cut)
blue
 
red
21.32×21.32 mm 20.1×20.1 mm
actual size
Actual size of 40ct Topaz (round cut, 21.32×21.32mm, Blue color)   Actual size of 38ct Ruby (round cut, 20.1×20.1mm, Red color)
 
Actual size is set for screen
Ring: Skin tone:
Ring width: 3.0 mm
Left finger image
Ring on left finger
Blue 40ct Topaz (round cut, 21.32×21.32mm) on a left ring and finger
64 mm
Right finger image
Ring on a right finger
Red 38ct Ruby (round cut, 20.1×20.1mm) 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
 127% vs 119%
Saved...
Ring diameter: 16.9 mm
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Actual sizes of 40ct Topaz Round (21.32×21.32mm, Blue) and 38ct Ruby Round (20.1×20.1mm, Red) 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, Ruby will face-up smaller than Topaz for a given carat weight, because it has higher specific gravity (4 vs. 3.53 - this means it's "heavier" compared to Topaz 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.


40 Ct Topaz (Round) 38 Ct Ruby (Round)
21.32×21.32 mm vs 20.1×20.1 mm
357 mm²   317.31 mm²
Face-up size outline for 40ct Topaz (21.32×21.32mm, round cut)
Face-up size outline for 38ct Ruby (20.1×20.1mm, round cut)
40ct Topaz Round (21.32×21.32mm)
38ct Ruby Round (20.1×20.1mm)
Difference: 13% (39.69 mm²)
40ct Topaz (Round, 21.32×21.32mm) has approx. 13% more face-up area than 38ct Ruby (Round, 20.1×20.1mm).


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