Wales completed a third clean sweep in eight seasons with a hard-fought victory over a gritty French side, emulating the feat of the legendary Welsh sides of the 1970s.
Wing Alex Cuthbert beat four French defenders to run in the only try during the first half with full-back Leigh Halfpenny adding the conversion and three penalties to spark jubilant celebrations in Cardiff.
And Gatland was quick to praise the professionalism of his young squad, having clinched the slam with a starting XV containing nine players aged 25 and under.
When asked to sum up his side's key virtues, the New Zealander said: "Honesty and hard work.
"These guys have been a real credit to themselves, Wales and Welsh rugby in how they have prepared themselves.
"They are excellent professionals and they make our job as coaches easy as they do more than what we expect and what is required, and when you have players doing that and looking after themselves and doing all the extras it goes a long way to making us coaches look good."
Wales' win marked a fitting tribute to 1976 Grand Slam-winning skipper Mervyn Davies, who died on Thursday after a battle with cancer.
And current captain Sam Warburton, who was forced off at half-time with a shoulder injury, admitted the former number eight had been on the players' minds in the build-up to the clash.
He said: "It put a downer on yesterday's team run.
"We found out yesterday morning, I was actually given his book by somebody about a week ago so I was about to read that.
"I was well aware of how great he was as a player and to be on a list of Grand Slam-winning captains alongside players like him makes me feel very privileged."
And Gatland added that it was impossible to compare the current crop with the likes of Gareth Edwards, Barry John and Davies, who shone so brightly in the red jersey some 40 years ago, but predicted a great future may await this squad.
He said: "It's different time, different eras, professionalism versus the amateur era.
"It's hard. It would be interesting to see the teams of the 70s if they were playing South Africa, Australia and New Zealand every year.
"We are not at that level yet, but our big aim is to be consistent in beating the southern hemisphere sides and we have a young enough side that over the next few years hopefully we can do that.
"We have been down in games during this tournament and we have learnt how to win ugly and in the past that may not have happened.
"We have accepted the tag of favourites which has not always sat well on our shoulders. For a young side they have coped incredibly well and I think it can be good for us as a team over the next two or three years."
The Grand Slam, Gatland's second since arriving in the principality in 2008, makes him the outstanding candidate to lead the Lions Down Under in the summer of 2013.
The Lions want their coach for that venture to have a clear 12-month window to prepare for the tour, meaning if Gatland were to take the role one of his backroom staff, possibly attack coach Rob Howley, would take the reins for next season.
But Gatland would not discuss the post, and even joked that the Lions may not be able to meet his financial demands.
"Perhaps I can think about that tomorrow. I know I am in the frame and the union have given me support for that," he said.
"If the offer came along I have said it would be a huge honour, but there are a lot of things to put in place before that and we don't know what their requirements are and I'm not sure whether they can afford me either."
France coach Philippe Saint-Andre cut a dejected figure after seeing his side end the tournament in fourth place after picking up one draw and two defeats from their final three matches.
That left Les Bleus, who registered penalties through Lionel Beauxis and Dimitri Yachvilie (2) as Wales' tryline was not breached for the third straight game, with their worst record in the championship since 2001.
But the former Gloucester and Sale boss was magnanimous in his praise of Wales.
He said: "Congratulations to Wales they deserve it, it was a very tough game but we know to win the Grand Slam is not easy and they did it.
"Today was a very big contest but they won so congratulations to them.
"They have a young generation of players and a good staff and I think they deserve it and it's good for the pubs of Cardiff because their fans will drink a lot of beer.
"They are the winners and in sport you only remember the winner, not the ones who finish second.
"We are sad and disappointed as it was not a bad performance but we finished fourth in the Six Nations."
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