Via Alchemy table in Viron....i guess if you use 3x strange items from Torsche u get some Wind/Fire/Ice stones from it.Get at least 50pcs each.Or try alchemy in range 2-6. - the easy way -
Or u can get them thru Alchemist in Auch,near Karjalein,but need some specific items to craft them...like Branch of wind+mana stone,not sure tho.