Had to replace a glass on an old pocket watch. The jeweller fitted and bevelled and of the shelf glass. Worth trying a jeweller for your gauge
Cheers
Mark
I replaced the beveled glass on a 50 lb gauge last year. It was an involved process. I will share details with you if you would like to contact me directly at alexbeamer@comcast.net.
I just took my bezel, and fortunately a sample glass, to a local glass and mirror shop. He cut out a circle and ground the bevel on it with a grinder or a belt sander - it works fine.