I don't contest the fact than you'rte a specialist zolotnik, but…
Nobody gives the answer to my question, "What silversmith is it", why just answer "I don't know who, but surely not Arnd", ok, you say that you learn a lot from decades, then in place of an abrupt answer, just say it's not from Arnd and you don't know who make it, or surely a silversmith you don't know and the quality of the work proves the fact.
It's not a good thing when somebody can't make an expertise only based on the fact he is the specialist of the thing, they are a lot of things nobody knows, and it's not a dishonour in that fact to say it?
To close the discussion about this unknown silversmith, just some words for the anecdote:
In my mercury gilding activity, they are sometimes customers, from Israel for example, who comes with russian works of art(always big value items, no small things as my brooch), I suppose they know the fact than if the piece seems to be modern, no possibility by me, but they are other people who surely don't take those precaution, as we can control our work with AFM(atomic force microscope), we know that it's impossible to see if it is modern or not when made with ancient gold and good craftsmanship, experts from english auction houses or museum people had been tested before I write that.
Then are you sure that in your collection they are no fakes which comes to the surface when a better specialist found it with a more performant technology?