Yes rarest of Black dials. You are slightly out of date with the Porcelain prices. Try $200++. I remember 15 years ago I was telling people to buy as many 16520’s as they could. Some though I was mad. Some listened and now don’t think I was crazy.
You were around in those days as well when we could buy a mint 16520 for £4-5k.
Good old days.
M.