Do all stones of the same mm size have the same size appearance?

[stepcutgirl]

I was reading an old thread the other day where one ps''r told another that her cushion shape of the same size would look larger than a round due to its shape. I may understand that if it was a rectangular cushion, but would a square cushion and a round both with the same mm size look the same or would one shape tend to look bigger even though it is not? Are there any particular shapes that simply lend themselves to looking bigger even though they are not?

 

[marcy]

A sqaure will look larger than a round of the same mm because of the corners.

 

[Fly Girl]

Comparing a 4 mm square to a 4 mm round. The surface area of the square is 4 times 4 or 16 sq mm. The surface area of the round is pi x radius squared, or 3.14 x 2 x 2 or 12.56 sq mm. 16 is larger than 12.56, so the square looks larger. Basically, if you overlap a round and a square, the corners of the square are not covered.

 

[stepcutgirl]

That makes sense. Thank you!

 

[chrono]

FlyGirl is correct. If you want to know which stone will appear larger, just calculate the total surface area. Just knowing the mm measurement is insufficient because the calculation for a circle, square, pear, trillion, rectangular, etc are all different.