Instructions
Look for a vertical seam through the pipe's bowl. This is an unmistakable indication that your pipe was cast from a mold. Real meerschaum is carved.
Rub the meerschaum with silver. If you see marks that look like graphite from a pencil, the meerschaum is not authentic.
Check the country of origin. Most genuine meerschaum pipes are manufactured in Turkey. While this doesn't guarantee authenticity, it is more likely that a Turkish pipe is made of genuine meerschaum.