I've never bothered with it before, but now I've seen some things I'd like in the Crystal Shop so I guess I need to start fragging, lol. What I wondered is, what are the best items to use? Is there a way to know what item will give a crystal and what won't? I thought it had to do with rarities, but I don't remember how. Do share please!

Items 'Rare' and 'Super Rare' give at least 1 crystal apiece guaranteed, I believe some super rares have a chance to give multiple - but I've personally never remembered getting extras. I'm not sure of the chances below that, but there are quite a lot of rare items in that range that can be pretty cheap. I believe it's rarities ranging from 65-99, but I could be mistaken on the number range.

Okay, thank you!

It is based on rarity, unfortunately I don't know the exact ranges on what gives you how many crystals (and I'm lagging right now too badly to find it). Hopefully someone else has it handy.

Personally when I sort the multiples out of my gallery (most of which are from vending), I pull everything worth less than 1k usually and frag it, anything I have less than 100 sP I buy extras to frag. I actually caught a <100 sP Rare last night and bought them all up.

[edit] I did manage to find it: R65 and under: 0-1 crystals R66 - R89: 1 crystal R90 - R98: 1-2 crystals R99: 1-3 crystals

I usually just frag all the junk I get from vending and quests, but if you're looking to buy specifically for fragging, I'd suggest buying "rare" to "super rare" items, since they always give crystals. Sometimes "super common" rarity items do as well, but it seems to be a matter of chance. From experience, it seems that "mundane" items don't give out crystals.

Thanks :)