Sure, that i've seen :) Sorry if i was unprecise on that matter. I'm wondering why have level 2 and 3 on jewels if they have no other function than the level 1 jewels? Or does the level 2 and 3 jewels have properties that arent found on level 1 jewels?
Some are considered more powerful so you'll need to invest in mixed sets to take advantage of them for some skills. That's my takeaway on the different slot sizes.