In addition to winning the Masters for the first time and becoming only the sixth male golfer to achieve a career grand slam, Rory McIlroy won $4.2m (€3.7m) at Augusta on Sunday, of which long-time caddie Harry Diamond will receive a significant share.

The pair were childhood friends growing up in Holywood, Co. Down, and Diamond represented Ireland as an amateur, but did not make it as a professional.

He became McIlroy's caddie in July 2017 following his split with JP Fitzgerald, and McIlroy said the Masters win was just as much Diamond's as it is his after being awarded the Green Jacket.

“I’ve known Harry since I was seven years old. I met him on the putting green at Holywood Golf Club. We’ve had so many good times together,” a tearful McIlroy said at his post-victory press conference.

“He’s been like a big brother to me the whole way through my life.

“To be able to share this with him after all the close calls that we’ve had, all the crap that he’s had to take from people that don’t know anything about the game, yeah, this one is just as much his as it is mine.

“[Diamond] is a massive part of what I do, and I couldn’t think of anyone better to share it with than him.”

Prior to McIlroy's dramatic play-off victory over Justin Rose, he and Diamond had won 19 times together on the DP World Tour and PGA Tour in addition to winning the Race to Dubai three times and the FedEx Cup twice.

According to Golf Monthly, caddies make an average salary of $2,000 (€1,760) per week on the PGA Tour as well as 5-10% of their golfer's winnings, depending on results.

With the win at Augusta, Diamond could be expected to earn around €370,000 for what is the most valuable tournament win of McIlroy's nearly 18-year professional career.

Last year, McIlroy won nearly €2.7m across the Majors, €6.5m on the DP World Tour, and $7.7m (€6.8m) on the PGA Tour when excluding all shared tournaments.

From the €16m total, Diamond is estimated to have earned €800,000 to €1.6m in addition to whatever salary McIlroy might pay him.

Diamond has a reported net worth of $2.5m (€2.2m), but it could be substantially more, and especially if the good times keep rolling.

Since Diamond joined him in 2017, McIlroy has won €35.3m on the DP World Tour, and €67.7m on the PGA Tour.

Both tours count the four Majors and the World Golf Championships towards their money lists, so there is some duplication in the totals.

Taking just the PGA Tour figure into consideration, Diamond is likely to have earned €3.4m at the very least caddying from his close friend.

Assuming a weekly salary €1,760, you could potentially add another €700,000+ in earnings over the past eight years.

McIlroy himself was named the world's second-best-paid golfer in 2024 with earnings of $83m, including $38m on-course and $45m off-course.

The Sunday Times estimated his net worth at £200m (€233m) in 2023.

Photo: Rory McIlroy of Northern Ireland celebrates with caddie Harry Diamond and the Masters trophy during the Green Jacket Ceremony after winning the 2025 Masters Tournament at Augusta National Golf Club. (Pic: Richard Heathcote/Getty Images)