18ct Diaspore (Cabochon, 18.93×12.62mm, Light Yellowish Green) vs 18ct Alexandrite (Cabochon, 18.36×12.24mm, Bluish Green)
Quick summary: When looked from above (face-up position), 18ct Diaspore (18.93×12.62mm, cabochon cut) appears 6% larger than 18ct Alexandrite (18.36×12.24mm, cabochon cut). See below how they compare side-by-side on a ring and finger.
| 18ct Diaspore (cabochon cut) |
vs
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18ct Alexandrite (cabochon cut) |
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light yellowish green |
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| 18.93×12.62 mm | 18.36×12.24 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
18ct Diaspore Cabochon (18.93×12.62mm, Light Yellowish Green)
and
18ct Alexandrite Cabochon (18.36×12.24mm, 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 Diaspore for a given
carat weight, because it has higher specific gravity
(3.73 vs. 3.4 - this means it's "heavier" compared to Diaspore 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.
| 18 Ct Diaspore (Cabochon) | 18 Ct Alexandrite (Cabochon) | |
| 18.93×12.62 mm | vs | 18.36×12.24 mm |
| 195.9 mm² | 184.28 mm² |
| 18ct Diaspore Cabochon (18.93×12.62mm) | |
| 18ct Alexandrite Cabochon (18.36×12.24mm) | |
| Difference: 6% (11.62 mm²) |
18ct Diaspore (Cabochon, 18.93×12.62mm) has approx. 6% more face-up area than 18ct Alexandrite (Cabochon, 18.36×12.24mm).
Popular comparisons:
- 34ct Diaspore (Cabochon, Light Yellowish Green, 23.4 x 15.6) vs. 1ct Emerald (Emerald, Green, 7.28 x 5.39)
- 2.7ct Ruby (Pear, Red, 10 x 7) vs. 3ct Ruby (Emerald, Red, 9 x 7)
- 1.5ct Tourmaline (Round, Light Red, 7.45 x 7.45) vs. 1.5ct Sapphire (Round, Light Blue, 6.84 x 6.84)
- 1ct Kyanite (Oval, Blue, 7.77 x 5.18) vs. 1ct Tanzanite (Oval, Blue, 8.07 x 5.38)
- 1ct Aquamarine (Oval, Light Blue, 8 x 6) vs. 1ct Spinel (Oval, Gray, 8 x 6)
- 1.16ct Diamond (Round, White, 6.82 x 6.85) vs. 1.2ct Diamond (Round, White, 6.82 x 6.86)
- 6ct Morganite (Cushion, Light Red, 12 x 10) vs. 3.5ct Sapphire (Cushion, Blue, 8.49 x 8.49)
- 1ct Alexandrite (Round, Bluish Green, 6.14 x 6.14) vs. 1ct Emerald (Emerald, Yellowish Green, 7.28 x 5.39)
- 1ct Sapphire (Baguette, Blue, 6.93 x 4.62) vs. 1ct Emerald (Emerald, Green, 7.28 x 5.39)