×
carat vs. color  length*  width*
  ×

(or examine a )
* size in mm (optional)

28ct Alexandrite (Round, 18.58×18.58mm, Bluish Green) vs 28ct Topaz (Round, 18.93×18.93mm, Blue)


Quick summary: When looked from above (face-up position), 28ct Topaz (18.93×18.93mm, round cut) appears 4% larger than 28ct Alexandrite (18.58×18.58mm, round cut). See below how they compare side-by-side on a ring and finger.

28ct Alexandrite (round cut)
vs
 28ct Topaz (round cut)
bluish green
 
blue
18.58×18.58 mm 18.93×18.93 mm
actual size
Actual size of 28ct Alexandrite (round cut, 18.58×18.58mm, Bluish Green color)   Actual size of 28ct Topaz (round cut, 18.93×18.93mm, 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 28ct Alexandrite (round cut, 18.58×18.58mm) on a left ring and finger
64 mm
Right finger image
Ring on a right finger
Blue 28ct Topaz (round cut, 18.93×18.93mm) 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
 110% vs 113%
Saved...
Ring diameter: 16.9 mm
USA UK Asia EU1 EU2
Actual sizes of 28ct Alexandrite Round (18.58×18.58mm, Bluish Green) and 28ct Topaz Round (18.93×18.93mm, 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.


28 Ct Alexandrite (Round) 28 Ct Topaz (Round)
18.58×18.58 mm vs 18.93×18.93 mm
271.13 mm²   281.44 mm²
Face-up size outline for 28ct Topaz (18.93×18.93mm, round cut)
Face-up size outline for 28ct Alexandrite (18.58×18.58mm, round cut)
28ct Alexandrite Round (18.58×18.58mm)
28ct Topaz Round (18.93×18.93mm)
Difference: 4% (10.31 mm²)
28ct Topaz (Round, 18.93×18.93mm) has approx. 4% more face-up area than 28ct Alexandrite (Round, 18.58×18.58mm).


Popular comparisons: