Can you counterspell items?

[Bibliophile]

Can you counterspell an item's spell-activation effect?

Basically, if a character has an item of Mage Armor, say 3/day (command word activated). Can another character (with mage armor prepared) counterspell the item? (to keep it from activating)

Also, what if the item is use-activated? (activates when willed to do so)

 

[der_kluge]

Can you counterspell an item's spell-activation effect?

Basically, if a character has an item of Mage Armor, say 3/day (command word activated). Can another character (with mage armor prepared) counterspell the item? (to keep it from activating)

Also, what if the item is use-activated? (activates when willed to do so)

Aren't you supposed to make a spellcraft check to determine which spell is being cast in order to counter it? I would say no, then, since a magic item has no somatic/verbal/material components, you would never be able to tell which item it was casting.

I suppose you could argue that you could use a dispel magic to counter it.