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1ct Topaz (Round, 6.5×6.5mm, Blue) vs 0.85ct Alexandrite (Trillion, 6.83×6.83mm, Bluish Green)


Quick summary: When looked from above (face-up position), 1ct Topaz (6.5×6.5mm, round cut) appears 15% larger than 0.85ct Alexandrite (6.83×6.83mm, trillion cut). See below how they compare side-by-side on a ring and finger.

1ct Topaz (round cut)
vs
 0.85ct Alexandrite (trillion cut)
blue
 
bluish green
6.5×6.5 mm 6.83×6.83 mm
actual size
Actual size of 1ct Topaz (round cut, 6.5×6.5mm, Blue color)   Actual size of 0.85ct Alexandrite (trillion cut, 6.83×6.83mm, Bluish Green color)
 
Actual size is set for screen
Ring: Skin tone:
Ring width: 3.0 mm
Left finger image
Ring on left finger
Blue 1ct Topaz (round cut, 6.5×6.5mm) on a left ring and finger
64 mm
Right finger image
Ring on a right finger
Bluish Green 0.85ct Alexandrite (trillion cut, 6.83×6.83mm) 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
 39% vs 41%
Saved...
Ring diameter: 16.9 mm
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Actual sizes of 1ct Topaz Round (6.5×6.5mm, Blue) and 0.85ct Alexandrite Trillion (6.83×6.83mm, Bluish Green) 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, Alexandrite will face-up smaller than Topaz for a given carat weight, because it has higher specific gravity (3.73 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.


1 Ct Topaz (Round) 0.85 Ct Alexandrite (Trillion)
6.5×6.5 mm vs 6.83×6.83 mm
33.18 mm²   28.92 mm²
Face-up size outline for 1ct Topaz (6.5×6.5mm, round cut)
Face-up size outline for 0.85ct Alexandrite (6.83×6.83mm, trillion cut)
1ct Topaz Round (6.5×6.5mm)
0.85ct Alexandrite Trillion (6.83×6.83mm)
Difference: 15% (4.26 mm²)
1ct Topaz (Round, 6.5×6.5mm) has approx. 15% more face-up area than 0.85ct Alexandrite (Trillion, 6.83×6.83mm).


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