Well, you probably answered your own question. If you see a discernable difference between ebony and plastic then you might assume you could tell the difference with an even harder material.

If you don't want to spend that much you might try the experiment I did and order some bone pins from Elderly's. They're not expensive and I'll bet they would do a decent approximation of ivory.

...Oh yeah, and did I mention.....the fossil ivory LOOKS very cool.