Newbie dumb question

Hello,
I have a question regarding people buying rare jewels.
Do those people want them unidentified or it doesnt matter if they are id/unid?
If it doesn't matter does selling a rare jewel unid increases its value?

Thanks for your time, kind of stupid question however I have started playing PoE recently and im still trying to find few things out.

Identified

E:Unless there is some recipe I don't know about....