carat vs. color  length*  width*

(or examine a single gem)
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20 Ct Sapphire (Baguette)


18 Ct Peridot (Oval)

yellowish green
18.81×12.54 mm 21.03×14.02 mm
actual size
Actual size of 20ct Sapphire   Actual size of 18ct Peridot
Actual size is set for screen Change
Ring: Skin tone:
Ring width: 3.0 mm
Left finger image
Ring on left finger
Blue 20ct Sapphire on a ring
64 mm
Right finger image
Ring on a right finger
Yellowish Green 18ct Peridot 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 20ct Sapphire Baguette (18.81×12.54mm, Blue) and 18ct Peridot Oval (21.03×14.02mm, Yellowish 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?

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 Peridot for a given carat weight, because it has higher specific gravity (4 vs. 3.35 - this means it's "heavier" compared to Peridot 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.

20 Ct Sapphire (Baguette) 18 Ct Peridot (Oval)
18.81×12.54 mm vs 21.03×14.02 mm
235.88 mm²   241.77 mm²
Face-up size outline
Face-up size outline
20ct Sapphire Baguette (18.81×12.54mm)
18ct Peridot Oval (21.03×14.02mm)
Difference: 2% (5.89 mm²)
18ct Peridot Oval (21.03×14.02mm) has approx. 2% more face-up area than 20ct Sapphire Baguette (18.81×12.54mm).

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.