I have been making and playing bones for the last few years but mine are all wood. My father uses a lot of bone in his carving and scrimshaw. He soaks fresh bone in a lye solution and then polishes it with successively finer sand paper and uses toothpaste for the final polish.

One possibility is a solution of white glue and water. An old friend of mine used to make sand daollar jewelry and his first step was to soak the sand dollars in a white glue solution. I have seen him drop a large sand dollar on a concrete floor without harm to either the sand dollar or the floor.

I don't think the bone will be too brittle. I say go ahead and play them.