O.K so it looks like these are diamonds. Which is actually pretty cool that like Rumple could turn things into gold, she could do the same only with diamonds. venivincivivez mentioned that it’s been said that Dark!Emma will have a thing for diamonds (this is the source)
So as a chemist I find that very interesting because diamonds are not just beautiful, they are unbreakable. One of the most strong crystals in nature. Which I believe is something that Dark!Emma would wish to relate to.
But that’s not even the most interesting thing about diamonds. Did you know that the diamond itself is not that beautiful, but actually looks like a glass? What makes diamonds beautiful and sparkly at different colors are actually little metal impurities that get stuck with in it. So you see, what’s make it beautiful is actually the defects within it. Which is something Dark!Emma would be related to as well. I think she’s gonna feel like she has been “miss perfect” for too long and that it prevented her from shining.
So I don’t know if that’s the case, but if it is there is also a meaning behind this little fact, as usual.