15ct Alexandrite (Cabochon, 17.28×11.52mm, Bluish Green) vs 15ct Topaz (Cabochon, 17.6×11.73mm, Blue)
Quick summary: When looked from above (face-up position), 15ct Topaz (17.6×11.73mm, cabochon cut) appears 4% larger than 15ct Alexandrite (17.28×11.52mm, cabochon cut). See below how they compare side-by-side on a ring and finger.
| 15ct Alexandrite (cabochon cut) |
vs
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15ct Topaz (cabochon cut) |
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bluish green |
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| 17.28×11.52 mm | 17.6×11.73 mm | |
| actual size | ||
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Actual size is set for screen
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Ring:
Skin tone:
Ring width: 3.0 mm
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64 mm |
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Actual sizes of
15ct Alexandrite Cabochon (17.28×11.52mm, Bluish Green)
and
15ct Topaz Cabochon (17.6×11.73mm, 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.
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.
| 15 Ct Alexandrite (Cabochon) | 15 Ct Topaz (Cabochon) | |
| 17.28×11.52 mm | vs | 17.6×11.73 mm |
| 163.23 mm² | 169.29 mm² |
| 15ct Alexandrite Cabochon (17.28×11.52mm) | |
| 15ct Topaz Cabochon (17.6×11.73mm) | |
| Difference: 4% (6.06 mm²) |
15ct Topaz (Cabochon, 17.6×11.73mm) has approx. 4% more face-up area than 15ct Alexandrite (Cabochon, 17.28×11.52mm).
Popular comparisons:
- 1ct Alexandrite (Cabochon, Dark Purple, 7.02 x 4.68) vs. 1ct Alexandrite (Trillion, Bluish Green, 7.21 x 7.21)
- 1ct Alexandrite (Cabochon, Bluish Green, 7.02 x 4.68) vs. 1ct Emerald (Cabochon, Green, 7.8 x 5.2)
- 1ct Alexandrite (Cabochon, Bluish Green, 7.02 x 4.68) vs. 1ct Emerald (Emerald, Green, 7.28 x 5.39)
- 12ct Alexandrite (Cabochon, Bluish Green, 16.08 x 10.72) vs. 1ct Alexandrite (Emerald, Bluish Green, 6.55 x 4.85)
- 1ct Alexandrite (Cabochon, Bluish Green, 7.02 x 4.68) vs. 1ct Diamond (Cabochon, White, 7.14 x 4.76)
- 12ct Alexandrite (Cabochon, Light Bluish Green, 14 x 11) vs. 4ct Sapphire (Oval, Dark Blue, 11 x 9)
- 3.24ct Alexandrite (Cabochon, Bluish Green, 10.4 x 6.93) vs. 3.24ct Tanzanite (Oval, Blue, 11.94 x 7.96)
- 3.24ct Alexandrite (Cabochon, Bluish Green, 10.4 x 6.93) vs. 3.24ct Amethyst (Cabochon, Dark Violet, 11.61 x 7.74)
- 1ct Alexandrite (Cabochon, Bluish Green, 7.01 x 4.67) vs. 1ct Emerald (Emerald, Green, 7.26 x 5.38)