Often you don't see the grain easily, or the nerve hole. This set I recently bought shows little of the nerve hole or grain, though I show one there that does show them:
http://www.antiquegamblingchips.com/Ivories_Josephine.htm

If you don't see the grain right off, look carefully at the rim or ends of the chip; almost always you find some there. More about ivories here:
http://www.antiquegamblingchips.com/distinguish_iv_bon_cel.htm

Yours look to be ivories for sure.

Robert