erbrousman,
Welcome to TreasureNet. I would need a much higher resolution picture of it to make an identification of ivory on it. What does the back look like? Does it look like it was mounted on something? If you look at it with at least 10X, if it is bone there will be many small pores left from when the bone had a blood supply. If it is relatively modern plastic/celuloid, you might see bubbles or mold marks from casting.