The Sharks bagged a bonus-point victory in the Premiership Rugby Cup opener, which served as a curtain raiser for England's domestic season.
Saints gave it their all and replied through tries from Teimana Harrison and Alex Coles, but they rarely looked like claiming the win.
That was to be expected as Sale named a far more experienced side, which included several summer recruits.
And Diamond was pleased with the efforts of his side, particularly during the formative stages of the game.
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"We played reasonably well and in the first 20 minutes I thought we were clinical," Diamond said.
"We could have been a few more scores up but overall I was pretty pleased and it was a good step forward for us.
"We've got a good squad, strength in depth and we can afford to change the front row now.
"But we're not getting carried away, it was a good run-out for both teams and we're happy."