My Rubellite Tourmaline measurements

[Aussiewen]

Hi everyone,
My latest purchase from a second hand jewellers has lead me to believe my tourmaline perhaps is bigger than what was stated. When I saw it in person I thought wow this gem is massive but it was said it’s 5.5 carat. I just got my ruler and it measured 12mm by 12mm . It’s like a Princess cut. Is there anyway I can roughly estimate it’s carat weight by these measurements?

Thanks
Wen

 

[mellowyellowgirl]

It can squeak in at 5-6 carats for 12 by 12.

I bought (but ultimately exchanged) a rubellite that was 5ish carats and it was 11 by 11. It was a squarish cushion.

 

[Aussiewen]

It can squeak in at 5-6 carats for 12 by 12.

I bought (but ultimately exchanged) a rubellite that was 5ish carats and it was 11 by 11. It was a squarish cushion.

Thank you so much