Justin Bieber is reportedly buying a diamond ring for Selena Gomez.

Beverly Hills jeweller Neil Lane has been tasked with designing the £650,000 item with friends close to the 'As Long As You Love Me' hitmaker believing he is getting ready to propose to his on/off girlfriend.

The jeweller has created engagement rings for a number of stars - including Britney Spears - and although he won't comment on clients, an insider has revealed Justin's plans.

The source told the Daily Star Sunday newspaper: ''Justin is planning to go through final designs with Neil in the next week.

''At the moment his favourite idea is a huge, canary yellow, princess-cut diamond surrounded by smaller diamonds and set in white or yellow gold.''

It is said Justin's schedule is being kept clear for Selena's 21st birthday in July - and it seems he's ''relentless'' pursuit is paying off.

The insider added: ''Justin kept relentlessly pursuing her with text messages, emails and phone calls, despite the fact that she dumped him last year.

''Justin's mum Pattie also put pressure on Selena after coming to the conclusion she was the only one who could keep him on the straight and narrow.''