The formation saw United win 3-0 at St James' Park in the Premier League, and Ferguson says that he could use the system again.
"I wanted to try the diamond again after some success against Cluj [in the Champions League], which is not an easy place to go to, and against Newcastle in the Capital One Cup," he told MUTV.
"It worked very well for us. Obviously there were moments in the second half when we felt we had to change.
"The diamond closes off the midfield. The only problem is when the ball goes out wide, how far your midfield gets separated. If you try to keep it tight in the centre of the field, then the opposition have to go wide."
Ferguson added that he is encouraged to use the diamond formation following their previous success over Cluj and Newcastle.
"Okay, we took a gamble today because Newcastle are so big up front and they're good crossers of the ball," said the 70-year-old. "But the football we played from the central midfield positions through Cleverley, Kagawa, Rooney and Carrick was terrific.
"We played so well on Tuesday against a decent team. People look at the name Cluj and say they expect United to win, but they are a decent side.
"And because we played so well on Tuesday, I thought we should find out how far we can go with that diamond system."
United are second in the Premier League table with 15 points from seven matches, four points off the pace.