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30ct Alexandrite (Emerald, 20.3×15.04mm, Bluish Green) vs 30ct Topaz (Emerald, 20.68×15.32mm, Blue)


Quick summary: When looked from above (face-up position), 30ct Topaz (20.68×15.32mm, emerald cut) appears 4% larger than 30ct Alexandrite (20.3×15.04mm, emerald cut). See below how they compare side-by-side on a ring and finger.

30ct Alexandrite (emerald cut)
vs
 30ct Topaz (emerald cut)
bluish green
 
blue
20.3×15.04 mm 20.68×15.32 mm
actual size
Actual size of 30ct Alexandrite (emerald cut, 20.3×15.04mm, Bluish Green color)   Actual size of 30ct Topaz (emerald cut, 20.68×15.32mm, 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 30ct Alexandrite (emerald cut, 20.3×15.04mm) on a left ring and finger
64 mm
Right finger image
Ring on a right finger
Blue 30ct Topaz (emerald cut, 20.68×15.32mm) 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
 89% vs 91%
Saved...
Ring diameter: 16.9 mm
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Actual sizes of 30ct Alexandrite Emerald (20.3×15.04mm, Bluish Green) and 30ct Topaz Emerald (20.68×15.32mm, 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.


30 Ct Alexandrite (Emerald) 30 Ct Topaz (Emerald)
20.3×15.04 mm vs 20.68×15.32 mm
283.94 mm²   294.64 mm²
Face-up size outline for 30ct Topaz (20.68×15.32mm, emerald cut)
Face-up size outline for 30ct Alexandrite (20.3×15.04mm, emerald cut)
30ct Alexandrite Emerald (20.3×15.04mm)
30ct Topaz Emerald (20.68×15.32mm)
Difference: 4% (10.7 mm²)
30ct Topaz (Emerald, 20.68×15.32mm) has approx. 4% more face-up area than 30ct Alexandrite (Emerald, 20.3×15.04mm).


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