Need weight estimation formulas for Sapphires!

[Nicrez]

Ack! I have the dimensions of a stone, but need to know total carat weight...help! i only remember diamond''s estimations...

Measurements are: 18.20 x 10.21 x 9.59 mm

 

[Kismet]

This web site is roughly accurate, or at least it was accurate for the few stones I input.

 

[MustangFan]

Cool site!

I put in the dimensions for my sapphire and it was about .14 ct off, not bad!

 

[Nicrez]

Thanks Kismet! This will totally help for weight estimations from here on in. I am so lazy to root through my stuff in storage for my old GIA formulas, and even then this is FAR better than doing so much math!