before you do anything make sure it's waterproof. It would be a dick move to ruin a family heirloom because you had to know what it was made out of.

An easier way might be to take it to an antique dealer who would probably know what it is off the top of their head and would probably do it for free.

There's only one way of knowing. And it'll only cost you $250k, so it's totally worth it.