Ivory consists of dentine which is present in the tusks and teeth of animals and cross-section of different ivories gives you a different look into the inherent patterns. But though there are reputed dealers selling 100% original and legal ivory, an equal number of scammers sell fake ivory. So did you buy real or fake ivory artifacts?
There are numerous subtle differences that are visible to even untrained eyes, as many fake ivory products are crafted from reconstructed animal bone powder, but the color, texture and weight of the sculpture is very different. Dentine has little collagen and large amount of calcium phosphate which shows wear and tear over time. And ivory is sourced from wooly mammoths, elephants (now banned) as tusks while the teeth of wild boar, hippo, whales, and walrus are also considered as ivory. Some specific features that are consistent with natural ivory include high gloss with silky feel, inherent inter-sectional arches that are visible when holding it lengthwise and variations when you look down into it.
While plastic, bone powder, antlers and bone sculptures have a different weight and feel. To start with there are no Schreger lines. Bones have small channels as nerves and blood vessels go through it. It may not be visible to all but if you put light behind it, they appear as dots and dashes. While antlers have a darker color with honeycomb patterns all through the center, plastics on the other hand are lighter with an artificial look. However, you need to be conversant with ivory before you can make out the difference so it is bets to buy from top ivory traders and dealers as they provide you with authentic material at affordable prices. Check out genuine mammoth ivory art at http://www.mammothivory.info/