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4ct Amethyst (Radiant, 10.03×10.03mm, Violet) vs 4ct Tanzanite (Radiant, 9.28×9.28mm, Blue)


Quick summary: When looked from above (face-up position), 4ct Amethyst (10.03×10.03mm, radiant cut) appears 17% larger than 4ct Tanzanite (9.28×9.28mm, radiant cut). See below how they compare side-by-side on a ring and finger.

4ct Amethyst (radiant cut)
vs
 4ct Tanzanite (radiant cut)
violet
 
blue
10.03×10.03 mm 9.28×9.28 mm
actual size
Actual size of 4ct Amethyst (radiant cut, 10.03×10.03mm, Violet color)   Actual size of 4ct Tanzanite (radiant cut, 9.28×9.28mm, Blue color)
 
Actual size is set for screen
Ring: Skin tone:
Ring width: 3.0 mm
Left finger image
Ring on left finger
Violet 4ct Amethyst (radiant cut, 10.03×10.03mm) on a left ring and finger
64 mm
Right finger image
Ring on a right finger
Blue 4ct Tanzanite (radiant cut, 9.28×9.28mm) 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
 60% vs 55%
Saved...
Ring diameter: 16.9 mm
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Actual sizes of 4ct Amethyst Radiant (10.03×10.03mm, Violet) and 4ct Tanzanite Radiant (9.28×9.28mm, 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.


4 Ct Amethyst (Radiant) 4 Ct Tanzanite (Radiant)
10.03×10.03 mm vs 9.28×9.28 mm
95.57 mm²   81.81 mm²
Face-up size outline for 4ct Amethyst (10.03×10.03mm, radiant cut)
Face-up size outline for 4ct Tanzanite (9.28×9.28mm, radiant cut)
4ct Amethyst Radiant (10.03×10.03mm)
4ct Tanzanite Radiant (9.28×9.28mm)
Difference: 17% (13.76 mm²)
4ct Amethyst (Radiant, 10.03×10.03mm) has approx. 17% more face-up area than 4ct Tanzanite (Radiant, 9.28×9.28mm).


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