Why would anyone buy something where the quality of the jewelry was not known.

I can't imagine that the vendor is choosing anything more than borderline quality stones.

Now if I were a wealthy person who wanted to make a huge splash, I might consider saying to a concierge, "Look, I want you to get me an xx quality pair of sapphire earrings and put them into a sapphire martini for my guest here... and charge me whatever you like."

But this looks like a ripoff for vanity purposes only.
R.