I've searched like crazy but can't find a match for this. It sure looks like a royal order of some kind, though. Really neat find! Sorry you haven't gotten help on this one.
Definitely a neat find.
What do you mean by royal order? Serious question.
I'd start looking from UK. THat coat of arms looks a lot like one of Kensington, uk. The bottom right part does not look quite the same, but it is fairly close. Didn't find a match yet but who knows...
Voriax
It’s always possible it’s a heraldic themed civilian pendant without a true specific meaning I suppose?
https://www.etsy.com/listing/199461565/heraldic-coat-of-arms-star-enamel-gilt?show_sold_out_detail=1
Really nothing on the reverse?
None mark of attachment or something another,
or some letter?