Circle Brand Vintage Glass Pocket Watch Crystal 18-14/16 (~42.7mm) - NOS

Circle Brand Vintage Glass Pocket Watch Crystal size 18-14/16 = ~42.7mm (marked) with a thickness of ~1.1mm. Typical Mi-Concave Pocket Watch profile. While still likely well over 100 years old, in my 40 years of experience with them I've not found the older crystals to be any more or less brittle than anything you could find today. That said, they are quite likely dirty and need serious cleaning.  I have a supply of crystals that numbers in the hundreds of thousands so I can usually supply just about any size Watch Crystal you need (glass or acrylic) so feel free to inquire. Images do an adequate job of representing the item.