Hi everyone -

I've been give a man's 18ct yellow signet ring to re-size. I've done many before, always by tapping on a mandrel, as they've only needed to go up 2 sizes or less. But this one has to go from size M to Q. The shank is 4mm at the widest down to 3.6mm where it's worn. D-shaped with a high profile and 1.7mm thick. So there's plenty of metal, but can this be made so much bigger by tapping?

I know I could add gold, but a couple of things concern me. The face is engraved (though not seal engraved) and I wondered if heat - even annealing - might soften the crispness of the engraving? Is there any way to protect it? Also, there is a faint shadow line from the original solder and annoyingly, it's about 1.5mm away from the hallmark. I can be precise and mask the hallmark, but can I solder that close to it without damage?

I'd be grateful for your thoughts please!