I only know about this test because my grandmother used to be an antique dealer back in the day. If you want to know if it's bone or ivory, do the following test.
The test consists of heating up the point of a needle until it's red-hot and then pricking what you believe is your ivory carving. If the needle goes in, it's plastic; if not, it's probably ivory, or at least bone.
Also, what else did you get in that haul you posted in the mail thread?