Mexican 925 Silver Carved Stone Face in a Sundial Pendant Necklace has the number P18 or PJ8 on the back. It is a much loved piece, and some of the writing is hard to make out. There is an eagle, so that dates it a bit. The chain is 28 inches long. The pendant is 3 1/2 by 2 1/2. The stone is blackish, greenish, grey color. I do not have a gem tester, but it looks like either Obsidian or Labradorite. It weighs 1.64 ounces.