Portrait coming
Every piece is drawn, made and finished by hand in small runs. That is why the collections are small, and it is why the metal is solid. It would be easier and far cheaper to make something thin and plated. It also would not last, and there is already plenty of that.
The rule is simple: nothing below 14k gold filled, and no imitation stones. If a piece can be worn in the sea it says so, and if it cannot, that says so too.
Collections come out seasonally, built around a few hero pieces, at around fifty pieces each. Small runs mean a piece that sells out often stays sold out, and it also means most things can be made again in a different length or a different stone if you ask.