I have every confidence in that the owner would not even dare to have nothing like nail varnish remover anywhere near their pen collection. I will post on here once if I find anything out.
Yes Walter, the ring goes all around the pen.
Oh bugger..
been found out..
I had Made the pen and was with me for nearly a month prior to them taking it and there was no signs of marking. 


Any way.. I have had a very sharp needle, golds sewing box has been attacked. The finish has not laminated and there is no air gap under the marked area..
I don't think its worth stripping down wither as I don't believe I will ever find out what it was or is now after reading you experienced replies..