Things You'll Need
Instructions
Test the weight of the ivory. Real ivory is heavy, and a resin or cast won't be as heavy as the real thing. If the piece of ivory feels heavy, then chances are you're dealing with the real thing. Further investigation will help you narrow it down.
Look at the number of layers in the ivory. Hornbill ivory is a single, solid piece that's dense and hard and closely textured. Walrus ivory and sperm whale ivory only have two layers. The inner dentin layer is smooth and marbled, and the outer dentin layer is hard and dense. These two types of ivory are hard to distinguish from one another, but sperm whale ivory has a larger, inner layer; and they're used to make small objects. If there are more than two layers, then you don't have walrus or sperm whale ivory.
Examine the cross section. Elephant ivory and hippo ivory both have multiple layers, but differ in cross section. Elephant ivory has a feature called "Lines of Retzius," which are intersecting lines that form diamond-shaped cross patterns. Hippo ivory lacks this feature, but aside from the lines it's similar to many types of elephant ivory.