SHOW GLOBES YEA

So,
this beautiful shiny little trinket is not jewellery, it is in fact a show globe (also known as show jar).
It was popularly used in Apothecary windows throughout Europe and the US (later on) and even as

early as in the Roman empire.
I don't actually know if they were used in Italy during the renaissance but I've decided they're so shiny I don't even care. 

They were simply a kind of sign. You hung it in the window or outside the door and people would know that the place sold medicine. Or potions. In this case potions. And in this case, it will not be a shop but a royal alchemy lab, and the Royal Alchemy Lab will have its own show globe. A ROYAL one.
Ohohohoho...

Thinking the character will also be wearing a small one, as that did also occur. People did wear them. Well, not people, alchemists and apothecaries and such.

So, that's my prop idea. I'll get back to you on the rest.