There are two ways to work out whether an object is made from ivory as opposed to bone: examining the object's texture and color and carrying out the hot pin test. Dealer appraisals and chemical tests can provide a definite answer as to whether an item is genuine ivory.
The item should feel relatively heavy and solid when held in the hand, as ivory is very dense. However, bone can also feel solid and heavy, so weight and density alone are not guarantees that an item is genuine ivory.
The next step involves running the fingers over the item while paying attention to the texture. Ivory is extremely smooth, so if pockmarks or other roughness is present on the surface, the object may be made from bone.
Finally, examining the item under a magnifying glass can provide visual clues. Ivory is a lustrous material and sometimes has a yellowish hue. Schreger lines are a good indicator that the item is ivory. Darkened dots, pits and flecks in the surface, however, are indicators that the material is bone.
The hot pin test is another way of checking an object at home. A pin is heated in a flame for a few seconds, then touched against a discreet spot on the object. If the item is ivory, the pin does not leave a mark. If the item is made of plastic, the pin leaves a tiny dent behind. If the item is bone, the area where the pin touched the object smells faintly of burning.
As some plastics are valuable in their own right, it is good to ensure that the item is not made of plastic before performing the hot pin test.