I think that jewelry should have a property of showing off, so hidden private key wouldn't work that well. You need to have some mechanism how to show status. And that nicety factor was driven mostly by women decorum.
That's just a question of recognizable design and enough marketing spend, i.e. branding.
It's well known that people pay a major premium for things solely because they have words printed on them like "Calvin Klein", "Guess?" or "YSL". Jewelry branding is actually easier to make visually recognizable than clothes.
People don't pay a premium for the label, they pay a premium for the middlemen who host the label, because that is a presumably exclusive group and culture that they have access to.
