Diamond's men held off a spirited fightback from Gloucester to claim their fourth win from six Premiership outings after edging a hard-fought encounter at a rain-soaked Edgeley Park.
Sharks skipper David Seymour crashed over the line in the first half and a conversion and a penalty from fly-half Nick MacLeod helped the hosts into a 10-0 half-time lead.
But two penalties from Tim Taylor got Gloucester off the mark after the restart and a late try from centre Henry Trinder, which Taylor failed to convert, set up a grandstand finish.
Diamond said: "We did enough just to win and I think that's testament to the lads and how they stuck together and delivered.
"It was a bit hairy in the last 10 minutes but we held on and I'm very happy.
"Gloucester are a top-four side every year and we wanted to come away with four points and we did that.
"We take every game as it comes but it's going well."
Diamond - who will face a Rugby Football Union disciplinary panel on Tuesday over an incident during September 23's clash with Northampton - also reserved special praise for Seymour, who has enjoyed an outstanding start to the campaign.
Diamond added: "He leads by example and that's why he stays as captain."
Gloucester head coach Bryan Redpath was left deeply frustrated after his side's inept first-half display.
He said: "We didn't have any balance in our game and that's why we were 10-0 down at the break.
"The conditions made it like that but we didn't respect the conditions.
"You can't come to an away ground - or any ground - and think you can play from in your half. You just can't. You have to respect the game more because rugby is about territory."
Redpath was also left waiting on the diagnosis of full-back Olly Morgan, who sustained a finger injury and was replaced shortly before half-time.
As Morgan fielded a crossfield kick, he was tackled into touch and slid into the railings at the side of the pitch.
Redpath added: "Olly Morgan has damaged his finger with a fairly deep cut.
"These things can occur when you have a narrow touchline and he caught his hand on a sharp bit of of the metal railings.
"He's split between his fingers quite badly and hopefully there is no nerve or tendon damage but we don't know that yet.
"We'll have to wait and see. It's horrible for him because he never gets much luck."
Gilbert has released a new line of rugby cleats. The Gilbert Virtuo 8S is part of the exciting new product. Check it out.
The Barbarians are one of the top invitational rugby sides with a long history and classic rugby jersey.
The Nike Tiempo is a solid rugby cleat and one of few styles still made from full-grain natural leather.
The Lions get ready for their matches with this green training jersey. It's what the players wear. Get in the Gear!
A cool looking all black rugby cleat with the high performance adidas is known for. Get in the Gear!
Wear the crest of the British and Irish Lions on your t-shirt. A great look for the summer.
$29.99
The Lions are ready to get their Australia tour underway. They arrive in Perth on Monday.
The New Zealand All Blacks training jersey for 2013/14. Get in the Gear!
The USA Rugby Pro Alternate rugby jersey is perfect for any fan of the Eagles. Get yours to wear during the summer Test matches.
The NEW All Blacks 2013/14 jersey has arrived at World Rugby Shop. Dare to wear the colors of the All Blacks.