I still haven't found that one. I saw an article a while back showing that style of mic. They said it was for measuring sheet thickness which would make sense for a jeweler.
Give me a call and stop by sometime. I'd still like to get that high dome 48mm bulls-eye crystal. I straightened the screw for your milling attachment but didn't make a new handle yet.
(Lydia, Anjuli and Jon-Jon)