Decoding Jewelry Marks: Understanding '514' and JB Maker Mark

Question
I have an ID bracelet that's fairly old.  It has a metal mark of "514" stamped on it (much like sterling's "928") and a Makers Mark of JB along with 1/20 12KGF.

I'm stumped on what the mark "514" stands for.  Can you help?

Answer
Greetings,

If it was an assay mark then you would have 12Kt gold....don't think so. It may be some weird shibuichi type material, but the  again the symbols would be characters rather than numbers.
Short of viewing the marks it's impossible to say with certainty, however your description sounds like a stock code rather than assay marks.

Cheers, P