Haha, Joel... I remember when you started the search to see which ones you had. I had to break back into the Thalmor Embassy... I used my horse and jumped the wall like a boss.
How much do you get for them? I never bothered collecting them all, but seeing that I have nothing else to do, I could search for them. Is it possible to sell them? I hope I didn't before I realized they weren't just 'Unusual Gems'.
They are a quest item. I don't think that you can sell them. What happens is that you make the crown and then you get the Prowler's Profit ability which means you get a BOATLOAD of gems everywhere you go. Every chest has quite a few gems.... even the rare type.