Apologies I did see the post asking for my email but with all the site changes I forgot to contact you, the inset is a cheap aftermarket type from Jules Borel only thing is it is an old example given to me a few years back when I bought a recon 6309 divers case, all the others I have seen appear to have a smaller lume pip.
This is a pic of the one on my Tuna and another example of an aftermarket insert.
I believe Harold and Noah do some good inserts.
Geran