You should own the book "Antique Gambling Chips", as Travis says in immediate above post. Worth it alone for reproduction of pages of many old gambling supply catalogs.

Here I copy-paste some writings I've done in the past. Probably more info than you wanted:

It is sometimes difficult to distinguish between ivory, bone and plastic chips, dice, tops, etc. With ivory you usually see a grain on some of the items, often at the edges................. "French ivory" is a plastic/celluloid where an ivory-like grain is printed on the item (usually on 4 of the 6 sides of a die), and the “grain” is wavy, but rather parallel or even -- artificial looking.........Real ivory has a grain (often the grain is blurry and faint) that is uneven and makes a cross-hatching (intersecting) effect, and the surface is smooth and buttery looking. Unfortunately, often the grain is not apparent on ivory items..................Bone is not ivory and is much inferior to ivory. It often fools people and is often smooth like ivory, but never shows the hallmark interlocking-cross hatching grain of ivory. Bone often has very short blackish lines, generally going in the same direction, often described as embedded whiskers, often porous surface, very small cracks or fractures on surface, while ivory is smooth..............I just experimented with a thin nail, pliers and a gas range. I tried to push the hot nail through the chips and got these results. The nail easily went through the regular plastic chip. It took about four tries in the same place to push the nail through a catalin (bakelite) chip; on the first try it left a small but sizable indentation. However, only very small dents were made in a thicker than usual bone chip and a thinner than usual ivory chip! Also, the “buring nail” should make a “burned hair”-like smell when applied to bone or ivory (as opposed to plastic).