Yeah im pretty sure its any of the crystals, i usually get them off the demons [crystals with timer] as there easy to kill and pick the ones up off the floor.
You use the scales to make the lenses, premortem ones are 100% resist from being turned to stone [bright blue]. Postmortem scales can be used but there not as good.
Any wepon really, i start with radiant so when the minions near me come out i can just wirlwind. Other times iv used a leafblade but theres not much difference in the damage [maybe 1-2 dps].
I have ML/SL/DI/HLA/Hit spell on weps.
Thunderz
*EDIT You can also put the lenses on your gorget aswell as you helm, witch is really handy if you, like me forget to keep checking how many charges are left on your helm