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8.5ct Amethyst (Radiant, 12.9×12.9mm, Violet) vs 8.5ct Tanzanite (Radiant, 11.93×11.93mm, Blue)


Quick summary: When looked from above (face-up position), 8.5ct Amethyst (12.9×12.9mm, radiant cut) appears 17% larger than 8.5ct Tanzanite (11.93×11.93mm, radiant cut). See below how they compare side-by-side on a ring and finger.

8.5ct Amethyst (radiant cut)
vs
8.5ct Tanzanite (radiant cut)
violet
 
blue
12.9×12.9 mm 11.93×11.93 mm
actual size
Actual size of 8.5ct Amethyst (radiant cut, 12.9×12.9mm, Violet color)   Actual size of 8.5ct Tanzanite (radiant cut, 11.93×11.93mm, Blue color)
 
Actual size is set for screen
Ring: Skin tone:
Ring width: 3.0 mm
Left finger image
Ring on left finger
Violet 8.5ct Amethyst (radiant cut, 12.9×12.9mm) on a left ring and finger
64 mm
Right finger image
Ring on a right finger
Blue 8.5ct Tanzanite (radiant cut, 11.93×11.93mm) 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
77% vs 71%
Saved...
Ring diameter: 16.9 mm
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Actual sizes of 8.5ct Amethyst Radiant (12.9×12.9mm, Violet) and 8.5ct Tanzanite Radiant (11.93×11.93mm, 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, Tanzanite will face-up smaller than Amethyst for a given carat weight, because it has higher specific gravity (3.35 vs. 2.65 - this means it's "heavier" compared to Amethyst 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.


8.5 Ct Amethyst (Radiant) 8.5 Ct Tanzanite (Radiant)
12.9×12.9 mm vs 11.93×11.93 mm
158.09 mm²   135.21 mm²
Face-up size outline for 8.5ct Amethyst (12.9×12.9mm, radiant cut)
Face-up size outline for 8.5ct Tanzanite (11.93×11.93mm, radiant cut)
8.5ct Amethyst Radiant (12.9×12.9mm)
8.5ct Tanzanite Radiant (11.93×11.93mm)
Difference: 17% (22.88 mm²)
8.5ct Amethyst (Radiant, 12.9×12.9mm) has approx. 17% more face-up area than 8.5ct Tanzanite (Radiant, 11.93×11.93mm).


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