Internet Horology Club 185
Pocket Watch Crystal

This topic can be found at:
https://ihc185.infopop.cc/eve/forums/a/tpc/f/3426047761/m/6271049171

October 09, 2005, 07:43
Jack Davis
Pocket Watch Crystal
I recently picked up a number of crystals and am unsure what the size designators are on the tags. Many of them have two numbers like this example. Would these numbers refer to lignes? The crystal is about 40mm in diameter. Thanks!

Jack


October 09, 2005, 22:02
Mike Miller
Jack,

The top number refers to the diameter in lignes. The bottom number refers to the curvature in height. Click on the following link for a more indepth discussion of this topic

Topic on crystal numbering system
October 10, 2005, 05:20
Jack Davis
Mike,

Thanks for the information and the link!

Jack
October 10, 2005, 07:31
Brian C.
Jack,
I sent you some info in an e-mail.
Brian C.