Thanks for the clarification.
1. Did not realize the gems were tradeable, since my other gilded gems were not.
2. I have a ton of things sitting in my Reward Items. Pretty sure I've picked and chosen 1-2 pieces I wanted, letting the rest sit in there until i was ready. Apparently I am mistaken.
3. My point, is why do they offer 4, when there are only 3. However, your answer to #1 essentially explains it.
I have not bought this, as the price is a bit high for 4 gems.
I do enjoy the 1 gem for 400, or for 990 if I don't feel lucky. Nice to know if I dont get the one I want,