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13ct Alexandrite (Cabochon, 16.47×10.98mm, Bluish Green) vs 13ct Topaz (Cabochon, 16.77×11.18mm, Blue)


Quick summary: When looked from above (face-up position), 13ct Topaz (16.77×11.18mm, cabochon cut) appears 4% larger than 13ct Alexandrite (16.47×10.98mm, cabochon cut). See below how they compare side-by-side on a ring and finger.

13ct Alexandrite (cabochon cut)
vs
 13ct Topaz (cabochon cut)
bluish green
 
blue
16.47×10.98 mm 16.77×11.18 mm
actual size
Actual size of 13ct Alexandrite (cabochon cut, 16.47×10.98mm, Bluish Green color)   Actual size of 13ct Topaz (cabochon cut, 16.77×11.18mm, Blue color)
 
Actual size is set for screen
Ring: Skin tone:
Ring width: 3.0 mm
Left finger image
Ring on left finger
Bluish Green 13ct Alexandrite (cabochon cut, 16.47×10.98mm) on a left ring and finger
64 mm
Right finger image
Ring on a right finger
Blue 13ct Topaz (cabochon cut, 16.77×11.18mm) 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
 65% vs 67%
Saved...
Ring diameter: 16.9 mm
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Actual sizes of 13ct Alexandrite Cabochon (16.47×10.98mm, Bluish Green) and 13ct Topaz Cabochon (16.77×11.18mm, Blue) 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.


13 Ct Alexandrite (Cabochon) 13 Ct Topaz (Cabochon)
16.47×10.98 mm vs 16.77×11.18 mm
148.29 mm²   153.74 mm²
Face-up size outline for 13ct Topaz (16.77×11.18mm, cabochon cut)
Face-up size outline for 13ct Alexandrite (16.47×10.98mm, cabochon cut)
13ct Alexandrite Cabochon (16.47×10.98mm)
13ct Topaz Cabochon (16.77×11.18mm)
Difference: 4% (5.45 mm²)
13ct Topaz (Cabochon, 16.77×11.18mm) has approx. 4% more face-up area than 13ct Alexandrite (Cabochon, 16.47×10.98mm).


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