carat vs. color  length*  width*

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

1 Ct Tourmaline (Round)


1 Ct Amethyst (Cushion)

light purple
6.51×6.51 mm 6.41×6.41 mm
actual size
Actual size of 1ct Tourmaline   Actual size of 1ct Amethyst
Actual size is set for screen Change
Ring: Skin tone:
Ring width: 3.0 mm
Left finger image
Ring on left finger
Violet 1ct Tourmaline on a ring
64 mm
Right finger image
Ring on a right finger
Light Purple 1ct Amethyst 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 Tourmaline Round (6.51×6.51mm, Violet) and 1ct Amethyst Cushion (6.41×6.41mm, Light Purple) 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 Tourmaline or Amethyst check what Amazon has to offer. You'll usually find quite a selection from many different vendors. Worth a check. For other high quality gemstones (Rubies, Saphhires, Emeralds) and especially Diamonds, I highly recommend JamesAllen.

Face-up Size

All things being equal, Tourmaline will face-up smaller than Amethyst for a given carat weight, because it has higher specific gravity (3.1 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.

1 Ct Tourmaline (Round) 1 Ct Amethyst (Cushion)
6.51×6.51 mm vs 6.41×6.41 mm
33.29 mm²   36.98 mm²
Face-up size outline
Face-up size outline
1ct Tourmaline Round (6.51×6.51mm)
1ct Amethyst Cushion (6.41×6.41mm)
Difference: 11% (3.69 mm²)
1ct Amethyst Cushion (6.41×6.41mm) has approx. 11% more face-up area than 1ct Tourmaline Round (6.51×6.51mm).

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.