The retailer overtook Signet in 2016 with a sales total of £565m.
Signet Jewelers had enjoyed a period of steady growth over the past three years, with sales figures of £447m in 2014 (financial year ending 31 January 2015) and £489m last year.
But Aurum’s sales exceeded Signet despite tailing the American giant by over £114m, at £374m revenue, in the year ending 31 January 2015.
Financial results show that the company has seen a 36% increase in luxury watch sales over the last year.
Brian Duffy, CEO of Aurum Holdings, said: “London and Heathrow outperformed the rest of the UK although all regions were positive with some excellent growth levels achieved in the major shopping centres of Bullring, Trafford, Meadowhall, Bluewater [and so on]. Price increases do not seem to have deterred the UK consumer.”