Marilyn Monroe once sang: "A kiss on the hand may be quite continental/But diamonds are a girl's best friend." It was true - if more than somewhat cynical - when Anita Loos penned the original witticism in Gentlemen Prefer Blondes, true when Monroe sang it in the film - and now, it seems, it is even true when we stand on the brink of recession.

According to new figures Britain is one of the few countries in the world experiencing a marked increase in diamond sales. Despite the war on terrorism and the bleak economic outlook, sales are up 14 per cent by volume on last year. Three of the largest diamond jewellery firms in London - De Beers, Mouawad and Bulgari - have all recorded record sales.

Manufacturers believe the growth in the popularity of diamonds is owing to three factors. One is the trend for celebrities to wear borrowed diamonds for premieres and parties. Another is the wish by couples in the wake of 11 September to express their commitment to each other by getting engaged - and marking the occasion with a diamond ring. Finally, some people just want to cheer themselves up.

The trend for celebrities to equate glamour with expensive gems is perhaps best expressed in the video of Nicole Kidman singing Somethin' Stupid with Robbie Williams. While most viewers might remember their performance for its barely controlled sexuality, it is also notable for the fact that Ms Kidman wore a diamond necklace worth £5.5 million.

Nowadays few female celebrities choose to face the paparazzi without a few sparklers. Mouawad - who provided Ms Kidman's necklace - recently set up a celebrity loan service where the famous are asked if they would like to wear pieces for personal appearances, photo shoots and parties. The service is remarkably successful. At May's World Music Awards in Cannes, Carmen Electra, Ursula Andress, Christina Aguilera, Sonique and Anastacia all wore Mouawad.

At the recent Royal Variety Performance in London, Bulgari decked out Jennifer Lopez, Cher, Denise Van Outen, Hear'Say and Samantha Mumba, while De Beers diamonds have been seen on Liz Hurley, Catherine Zeta Jones, Naomi Campbell, Kate Moss and Juliette Lewis. It's not just women who have succumbed: Prince, Lenny Kravitz and Jon Bon Jovi have all worn De Beers.

Paul Crawford, store manager at Mouawad's New Bond Street store, said: "We normally see lots more engagements in December before the New Year but this year it was October and November. In these uncertain and difficult times people seem to want more security and to let their loved ones know how much they care." Mouawad's products, however, are beyond the price range of most Londoners; the cheapest item of jewellery at its New Bond Street store is £500, the most expensive is a ruby and diamond necklace for £6.5 million.

At New Bond Street antique jewellers Bentley & Co, sales of all jewellery are up since 11 September. Sales manager Omar Vaja said: "It is not just the very rich who are buying, it is average London income earners on £40,000 to £50,000, and they are tending to spend thousands rather than hundreds."

Many jewellers report that the other country to have seen a noticeable rise in sales is the United States. A spokesman for De Beers said: "The UK and US market is showing incredible growth this year - in fact, the highest in the world - with diamond jewellery sales in Britain up 11 per cent in value and 14 per cent in pieces, over a record year."