Gem of fire?

I found a little gem that says it either gives a weapon 1d4 fire damage, or a piece of clothing cold resistance. Is this permanent?

To my knowledge .. yes ..
But be wary.. if used on something that already has a cold res .. the effects DO NOT stack.. and if used on a "flaming" weapon the activated effect of the weapon will place a 1d6 fire damage untill deactivated (at which point you'll loose both - because the 1d6 overwrites the 1d4 with a temporary property that is removed on de-activation -leving no fire bonuses at all )... ...

Aye very true...yes they are perma....i just never buy flaming weapons. Ya truly dont need fire till ya start facing trolls...and buy then youve picked up a fire gem and can use it on your frost/sonic/whatever weapon your currently using.

Eventually, you will find more than one of the same elemental crystal. If you use, say, 2 crystals of flame on the same weapon, it will will list the 1d4 fire damage twice, but it will only be calculated once each hit (the damage doesn't actually stack with the same amount of fire damage).

So if I have a crystal of flame and say, ice, they stack, yes?

Yes.

And once you get your weapon all crystalized, you have very colorful damage rolls.

Another caveat on the crystals, there's one that doesn't work on mage-staff type weapons (orange one, forget it's exact name, not an elemental damage crystal, but it adds a weapon property like keen or massive crits. Can't quite recall).

The orange one adds Keen