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4.5ct Spinel (Cabochon, 11.7×7.8mm, Red) vs 4.5ct Alexandrite (Cabochon, 11.57×7.71mm, Bluish Green)


Quick summary: When looked from above (face-up position), 4.5ct Spinel (11.7×7.8mm, cabochon cut) appears 2% larger than 4.5ct Alexandrite (11.57×7.71mm, cabochon cut). See below how they compare side-by-side on a ring and finger.

4.5ct Spinel (cabochon cut)
vs
 4.5ct Alexandrite (cabochon cut)
red
 
bluish green
11.7×7.8 mm 11.57×7.71 mm
actual size
Actual size of 4.5ct Spinel (cabochon cut, 11.7×7.8mm, Red color)   Actual size of 4.5ct Alexandrite (cabochon cut, 11.57×7.71mm, Bluish Green color)
Actual size is set for screen
Ring: Skin tone:
Ring width: 3.0 mm
Left finger image
Ring on left finger
Red 4.5ct Spinel (cabochon cut, 11.7×7.8mm) on a left ring and finger
64 mm
Right finger image
Ring on a right finger
Bluish Green 4.5ct Alexandrite (cabochon cut, 11.57×7.71mm) 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
 47% vs 46%
Saved...
Ring diameter: 16.9 mm
USA UK Asia EU1 EU2
Actual sizes of 4.5ct Spinel Cabochon (11.7×7.8mm, Red) and 4.5ct Alexandrite Cabochon (11.57×7.71mm, 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 Spinel for a given carat weight, because it has higher specific gravity (3.73 vs. 3.6 - this means it's "heavier" compared to Spinel 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.


4.5 Ct Spinel (Cabochon) 4.5 Ct Alexandrite (Cabochon)
11.7×7.8 mm vs 11.57×7.71 mm
74.83 mm²   73.15 mm²
Face-up size outline for 4.5ct Spinel (11.7×7.8mm, cabochon cut)
Face-up size outline for 4.5ct Alexandrite (11.57×7.71mm, cabochon cut)
4.5ct Spinel Cabochon (11.7×7.8mm)
4.5ct Alexandrite Cabochon (11.57×7.71mm)
Difference: 2% (1.68 mm²)
4.5ct Spinel (Cabochon, 11.7×7.8mm) has approx. 2% more face-up area than 4.5ct Alexandrite (Cabochon, 11.57×7.71mm).


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