Diamanti's fourth goal in five matches put the injury-hit Hammers ahead just before half-time, only for Arsenal to rally late on with an equaliser from the impressive Wales youngster Aaron Ramsey and Eduardo's headed winner.
Zola feels the Italian forward, signed from Livorno during the summer, epitomises the spirit needed.
"You see them on the pitch, the way they run and the way they chase," said the Hammers boss.
"There was a couple of times Diamanti was chasing back like a crazy man and that shows you how much the players care about this team."
Zola added: "I have told the players to continue what they are doing.
"We are getting to a point where all the hard work and commitment will come back to us. It is a matter of being strong mentally and I have no doubt we are destined for many good things.
"We will try to make it a good year for everybody.
"In my experience, every time something has been difficult in my life, I have always achieved what I was aiming for."