Kate Middleton
Kate Middleton has been setting trends in fashion, similar to the way Princess Diana, mother of Prince William, did years ago. Reuters

When Prince William proposed to Kate Middleton using his mother Princess Diana's 28-year-old dazzling oval blue 18-carat sapphire and diamond ring, many women might have fainted at first and then gone out to buy a cut-price version of the same.

Now the replica of Kate's engagement ring, estimated to be worth millions, has become a best-seller at Marks & Spencer. The retailer claims that the replica is their best-selling piece of jewelry ever.

The platinum-plated royal ring worth £18, designed by M&S, went on sale in March. The retailer is selling about 200 pieces a week.

Style guru and M&S design manager for footwear and accessories Kate Crossey told Britain's Daily Telegraph: Since the royal wedding, we've found that classic, vintage style pieces have become increasingly popular. Despite the big day being over, customers seem to be holding on to the royal trend as we continue to see sales grow.

Other high-street retailers are desperate to cash in on Kate's status as a style icon. Debenhams, a fellow high-street retailer, also reported a similar fashion in April when its £6 replica of the ring became its fastest-ever selling piece of jewelry.