Jewellery brand Michael Hill has launched a campaign to reward the ’world’s best couple’ with a diamond ring.

It’s asking couples from around the world to sign up at my22ct.com and complete a series of online challenges to win the 22-carat ring.

The activity launched this week in New York with an event starring US reality TV star Kim Kardashian, while search and social media agency Tamar has been appointed to build engagement through social media.

Michael Hill will be using Facebook, Twitter and blogger outreach work to help promote the campaign.

Company CEO Michael Hill said, “The contest is free to enter and we’re expecting some really creative entries from romancing couples around the globe.”

The web build and strategy was carried out by McCann Worldwide Sydney.