I very much doubt your watch left the factory with that “bullseye” crystal on it. That type of crystal was used on watches in the 17th, 18th, and possibly early 19th centuries. The concave spot on your crystal was often called a “pontil” mark, or perhaps more popularly a “punty” mark. The jury is out on why those facets are there. Everybody with an explanation is adamant that there explanation is correct. So I’ll stay out of it. Best of luck finding a replacement.
If you are desperate, you might check with White’s watch crystals, here:
http://www.whitescrystals.com/products.htmlClick to expand...