Having the Duchess of Cambridge wear your product might be considered to be the ultimate endorsement for a designer.
When she wore a £310 (S$620) black velvet coat by Libélula to the wedding of her and Prince William's friends Sarah Stourton and Harry Aubrey-Fletcher in January last year, it sold out in hours, reported The Daily Mail last June.
The coat had a waiting list of 300 before you could say ker-ching.
But British jeweller Links of London thinks otherwise.
The retailer claimed the association to the duchess has led to a loss of around £8.2m in revenue over the past year.
The duchess wore their £275 topaz Hope earrings for her official engagement photos with Prince William.
But now, Links of London has fallen victim to hundreds of websites selling counterfeit copies of its products, reported The (London) Sunday Times.
Ms Caroline Rolfe, Links of London's head of online, said: "The counterfeiters were a lot cleverer than we were at the time of (the duchess') wedding.
"We didn't have that much stock, so we started to sell out quite quickly... The counterfeiters took advantage of that by saying they had stock and people were duped into buying them."
She said that many of the fraudsters have even copied the look of the Links of London website, and they even paid money to ensure that search engines listed their pages first.
In response, the jeweller has hired an online brand-protection company, which has so far closed 1,026 fake websites, including taking legal action against a company in China.
Most of the fake jewellery is made in Asia and costs about 20 per cent less than the genuine products.
Links of London estimated that it has lost about £8.2m of sales to the counterfeiters in the past year.
The fashion choices of the Duchess of Cambridge have led to a surge in sales for the designers with the phenomenon called "The Kate Effect".
"Kate has driven the popularity of certain products, which have then become much more appealing to counterfeiters," said Ms Rolfe.
"We do not publicise the fact that Kate wears our jewellery. She isn't an official ambassador, she is just a fan of the brand, whereas a lot of the counterfeit sites have cottoned on to it and use a lot of pictures of her on their sites."
This article was first published in The New Paper.