John, I have collected ivory Netsukes for years & use a simple test to see if they are the real McCoy.I found that the striation method can be deceptive. You heat up a pin holding it with a plier. You insert the pin into an inconspicuous spot on the piece & then smell the odor. If it smells like burnt hair it's real ivory. Plastic & resin have a much different smell. Now, where would you find such a place on an ivory chip?????