In case you hadn't noticed, ASOS has teamed up with Diet Coke for Treasure Hunk – basically an excuse to look at dishy guys and win fancy prizes (ideal!) – and jewellery designer Katie Rowland (who counts Cara Delevingne and Eliza Doolittle among her fans) has created a super-spesh diamond necklace as one of the prizes. 

'I wanted to keep true to Diet Coke,' Katie told us. 'It seemed perfect to take the ring pull and create a pendant.' Besides drooling over Katie's 'mazing design, we also quizzed her on the v important (whether it's real or fantasy) process of buying an engagement ring. Here are her top tips…