Tramlines

Wozniacki shows off the giant diamond ring you get when your boyfriend’s worth £200m

Danish tennis star Caroline Wozniacki got engaged to golfer Rory McIlroy at New Year, provoking widespread feelings of warmth and wellbeing, and countless exclamations of "Aahhhhhh" at the happy news of one of sport's nicest young couples.

But those "aaahhhhhs" turned to "oooohhhs!" on Thursday as the 23-year-old showed off the giant diamond engagement ring that McIlroy has bought her to the appreciative crowd at the Australian Open.

Yet the Northern Irish golf superstar - who last year signed a deal with Nike worth £150 million - seems to have fallen short of the age-old rule of thumb that says men are supposed to splash out a month's salary on the ring.

The hefty chunk of rock - which is apparently a stonking eight carats - is not the sort of thing you'd find at Elizabeth Duke. It's impossible to know exactly how much it cost - colour and purity as well as size are hugely important in diamond prices - but it's been estimated at somewhere between £150,000 and £600,000.

A huge amount, yes... but McIlroy's sponsorship deal alone brings him a reported £850,000 a month. Add in the fact that he's got dozens of other sponsorship deals, and that he's pocketed around £25m in career prize money so far, and his total net worth is probably at least £200m.

But then again, it's probably just as well he didn't go for an even bigger ring. Caroline's sparkler is so heavy that she has to take it off to play; and if it were any bigger, we'd worry for her ability even to walk while lugging it around.

Caroline Wozniacki