The style is European, probably Germanic. That covers a vast amount of area, more than today's Germany.
The horizontal lines are from the "Petra Sancta" method of depicting colour in a black and white drawing and represent blue.
Because of the European style of the arms, I do not think that they have anything to do with the Prince of Wales, nor any other person of Royalty. Rather they are just 3 feathers issuing from a Count's coronet.
Above the helmet, which is probably steel, is the crest. A "panache" of 5 feathers issuing from a ducal coronet (nothing to do with Dukes, just the name of the coronet). This is a pan-European crest used as a space filler. Many, many families use the same crest there. (In Spain, crests are unknown, but artists use a panache as an artistic trick to fill up and balance a canvas.)
It is my opinion that this was a seal (for documents) and of European origin. There was a time, in Europe, when most business people and most tradesmen would use a seal, but did not have a coat of arms.
It is a handsome piece of jewellery and there is no reason (legally nor morally) why you should not continue to use it as a seal in your family.
Regards
Chas
