spell or fire damage?

I am a fireball elementalist, my primary skill being fireball. If I want to anoint an amulet, which will increase my fire damage more, fire damage or spell damage. Suppose, for example, I have 100 dps on fireball. Will "increase spell damage 15%" and "increase fire damage 15%" have the same impact on Fireball's dps?

Depends on what you trying to scale.

Spell dmg will only scale the initial hit but not ignite dmg - unless the skillgems says otherwise and spell dmg factures into ignites as well.

Fire dmg should scale both: Hit and ignite. However, if you really want to scale ignite dmg, then you should look into generic dot multi or fire dot multi dmg, since those will impact ignite the most and the initial hit isnt even that relevant for this particular playstyle.


So there isnt a "one size fits all" answer.
It really depends on what you are intending to do here.

thanks. that is very clear.