carat vs. color  length*  width*

(or examine a single gem)
* size in mm (optional)

1 Ct Alexandrite (Round)


0.7 Ct Sapphire (Emerald)

bluish green
6.14×6.14 mm 5.67×4.2 mm
actual size
Actual size of 1ct Alexandrite   Actual size of 0.7ct Sapphire
Actual size is set for screen Change
Ring: Skin tone:
Ring width: 3.0 mm
Left finger image
Ring on left finger
Bluish Green 1ct Alexandrite on a ring
64 mm
Right finger image
Ring on a right finger
Blue 0.7ct Sapphire on a ring
Your settings
Skin tone
Ring diameter
16.9 mm
Ring width
3.0 mm
Finger length
64 mm
Ring diameter: 16.9 mm
Actual sizes of 1ct Alexandrite Round (6.14×6.14mm, Bluish Green) and 0.7ct Sapphire Emerald (5.67×4.2mm, 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?

JamesAllen → high-quality blue Sapphires, high-end jewelry and competitive prices. Highly recommended.
Amazon → usually offers a good selection from many different vendors. Worth a check.

Face-up Size

All things being equal, Sapphire will face-up smaller than Alexandrite for a given carat weight, because it has higher specific gravity (4 vs. 3.7 - this means it's "heavier" compared to Alexandrite 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.

1 Ct Alexandrite (Round) 0.7 Ct Sapphire (Emerald)
6.14×6.14 mm vs 5.67×4.2 mm
29.61 mm²   22.15 mm²
Face-up size outline
Face-up size outline
1ct Alexandrite Round (6.14×6.14mm)
0.7ct Sapphire Emerald (5.67×4.2mm)
Difference: 34% (7.46 mm²)
1ct Alexandrite Round (6.14×6.14mm) has approx. 34% more face-up area than 0.7ct Sapphire Emerald (5.67×4.2mm).

Popular comparisons:

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Actual size is currently adjusted to screen.

If your screen (phone, tablet, or monitor) is not in diagonal, then the actual size of a gem, ring and finger will not be shown correctly.