Shine a black-light light source on it. If it fluoresces a strong deep red, I typically consider it ruby.
It looks like its large enough it can handle being cabbed and carved. Carving an intricate design on the cab dome, if done well, can give the stone a strong boost in value.
Also sapphire and ruby are both corundum. Color is what separates ruby from sapphire. To the best of my knowledge. Nice piece either way.
Pandora,
That has a beautiful color and size. I would cab it and set it for YOUR own wear. You have some wonderful memories attached to that stone and that my dear makes it priceless. I think you can make and awesome piece with it.
I have a huge red raw ruby that is 3x’s that size that may produce a cab about that same size but nowhere near the quality that I may get around to cabbing some day when I get the time. Just for the same reason.
All the very best.
Otter