Limited editions of prints by rising stars of the art world have staying power and are a surefire way to invest with confidence.
For established living artists, print-making can be a licence to print money. And for collector-investors, the right names can appreciate in value more predictably than any other artworks.

Here's how it works: an art gallery or print publisher commissions an artist to produce a limited edition of, say, 100 prints. They are offered for sale at a starting price. When a number have been sold, the remaining stock acquires scarcity value, and the price goes up. The last print can retail at double the starting price.

How do you know the price will go up? Simply ask the publisher whether he intends raising it. When he does, the value of the print you have bought will rise. You will know you have made a good buy when the publisher calls you to say the edition has sold out and he has a client willing to buy your print for more than you paid.

Example: Ray Richardson's oil paintings of tough-looking men with bull terriers now sell for up to pounds 10,000. To satisfy demand, Advanced Graphics published a huge 3ft by 3ft original lithograph by Richardson, titled Plash, showing a bull terrier jumping into water. At a starting price of pounds 425 (ex VAT) in January last year, it was a hit. In August, the publishers raised the price to pounds 500. In December, they raised it to pounds 750. There are now only five left.

This summer, to mark the '98 World Cup, Advanced Graphics also published Richardson's print Twinkletoes, showing a bull terrier heading a football, in an edition of 198. Its starting price was pounds 250 (ex-VAT). So far, a third have sold. At the end of this year, the price will rise to pounds 350. How do I know? Because I asked Louise Peck, a partner in Advanced Graphics.

Publishers need to communicate price rises to all the galleries and art consultants who also have copies of the same print in stock. So, to minimise paperwork, Peck tries to make a round of price rises at the same time - for example, at a year's end. Which means that buying a print at the right time can be like buying a new car under the old magic-letter numberplate system.

To stretch a point, on New Year's Eve, you could put down pounds 250 for a copy of Twinkletoes, a split second before Ms Peck slaps the new pounds 350 price tag on it, and make an instant pounds 100 profit. On paper, at least.

A lithograph by Richardson, One Man, His Dog and His Maisonette, showing a burly man pushing a bull terrier in a supermarket trolley up a slope, in an edition of 200, is for sale at pounds 250 at this weekend's Contemporary Print Fair at the Barbican. It is one of six prints commissioned by organiser Clive Jennings, in aid of The Big Issue (the artists have accepted a flat fee in lieu of royalties). Jennings' eye for best-selling names means that his Big Issue choices are as likely to rise in value as any. They are, besides Richardson, Bruce McLean, Peter Blake, Sir Terry Frost, Adrian Wiszniewski and Tom Hammick. Prices range from pounds 250 to pounds 400.

Frost, aged 83, is a renowned abstract painter and print-maker. A 1986 print of a dragon by the 40-year-old Glasgow artist Wiszniewski, originally sold for pounds 300, now commands pounds 1,500. Tom Hammick, 35, has established himself primarily as a print-maker. Bruce McLean, the 54-year-old painter, print- maker, sculptor, film-maker, architect and, most recently, ceramicist, lurches in and out of the limelight. Peter Blake, 66, was a prime mover in Sixties pop art. He did the Beatles' Sgt Pepper album cover.

Watch out for more print offers. The magazine Contemporary Visual Arts has just launched a free portfolio of four artists' prints, beginning with an outrageous original by Tracey Emin, Every Bodies Been There, depicting penetration from the rear.

The Contemporary Print Fair, Concourse Gallery, Barbican Centre, London EC2, today 10am-7.30pm, tomorrow noon-6.30pm (0171-436 4007). `Contemporary Visual Arts' is on 0171-823 8373