Investing in antiques and paintings is not as straightforward as investing in stocks and shares. For example, people can get very attached to their items or collections and may then be reluctant to cash in their investment. A golden rule for the investor in antiques or paintings is to ensure that whatever you buy is authentic and has not been changed or altered from its original state. It is inadvisable to make a purchase on a whim. And you should always seek impartial professional advice.

Art, like shares, can be a volatile market depending on whose paintings you buy. If the market goes off the boil, it can have the same impact as if you had stocks and shares in a company which goes into liquidation. You could lose everything, in value terms, but at least you would be left with the picture.

However, unlike shares, where there is readily accessible evidence as to their appreciation or otherwise over time, the only way you can judge the rise in value of a painting or antique is if that item is put back on the market - which doesn't happen very often.

Hence the dearth of statistics to determine whether antiques and art are wise investments.

Mr James O'Halloran, a specialist in Irish paintings and managing director of James Adam Auction Rooms in Dublin, says art investment can be tricky. When people approach him saying they want to invest £10,000 in a painting, he advises them the values of paintings can be volatile.

But if you examine the artist's track record, just as you would look at a company's track record, you will gain a good idea of whether the painting you buy will appreciate in value, he says. Mr O'Halloran warns: "It's very easy to make a bad mistake with a painting by buying it, thinking you're buying a bargain, that you've seen in some emporium somewhere around the country and you think `Gosh, you know that's a Jack Yeats and he's only looking for £20,000. I mean they normally make £80,000 so buy it quick'." Then it turns out not to be a Yeats and the vendor has vanished. Just as you would seek a stockbroker's advice before investing in shares, "in the same way more-in-tune people will ask us what we think of a particular artist, what we think of a particular painting".

Mr O'Halloran says that at Adam's and at "the more professional" auctioneers they don't have a vested interest in what they sell. The paintings belong to private individuals. Although Adam's gets a cut, "it doesn't really make a difference to me at the end of the day whether somebody buys lot 45 or 95 because neither of them are mine. Obviously I want to do the best I can for the vendor - that's what the auctioneer's job is - but I would not say that somebody ought to buy that particular one in preference to another." It is vital to buy from a reputable source where you can be guaranteed you're getting good title. The person selling the picture must have the right to sell it without any encumbrance; it must be theirs to sell. "People who buy from auctioneers the likes of ourselves and many others can be happy that they're getting good title," he says.

In many cases the auctioneer will know the vendor who is asked to declare that the items belong to them without encumbrance. Adam's also sends its catalogues to the art loss register in London where everything is scanned and "if anything turns up that had been reported stolen we get to hear about it, virtually instantly," he says.

But be warned that antiques and paintings tend to be more long-term investments. If your primary motive is to invest, do so in your 30s rather than in your 60s.

Mr Michael Jordan, a fellow of the Irish Antiques and Valuers Institute and director of O'Reilly's Auction Rooms in Dublin, says you would be "extremely wise" to spend money, whether £1,000 or £50,000 on antiques.

"The disadvantage in buying antiques as an investment is that you're very reluctant to sell. You should never buy antiques in order to make a profit, unless you're in that business. Buy them to enjoy them."

He advises people to seek expert advice to ensure that the piece being bought is in its original condition and hasn't been altered. "If you can buy it in the condition it was 200 years ago or 150 years ago, I say that, within reason, no matter what you pay for it now, so long as it's within the market value at this particular time, you cannot go wrong for its automatic increase in value." He says antique jewellery can be a sound investment, especially if you buy at auction where you pay the market price and VAT is paid only on the profit margin. The VAT you pay on new jewellery is an immediate write-off. Moreover, as soon as you have bought it, new jewellery becomes second-hand; so you wouldn't even get the price you paid for it minus the VAT - which includes the jeweller's expenses and profit margin - if you sold it the following day. However, the value of antique jewellery is often determined by what's in fashion. Jewellery has to be attractive to look at today. You can't wear something today that won't be fashionable until 50 years' time, he says.

For this reason, Georgian jewellery is currently undervalued: "It is not in fashion or in vogue at the moment. But there is a small appreciative market for it nevertheless, usually across the water and in the US." He predicts that Georgian jewellery will appreciate over the years. At present, it can sell for as little as £100 or £150.

The unique selling point of antiques is that they are precisely that - unique: "If you buy shares you might buy £5,000 worth of the one item. If you buy 10 articles of antiquity, you're buying 10 individual pieces and each has its own merits," he says. People who invest in silver or gold antiques are protected against any crash in the value of commodities: "You're not buying silver. You're buying an antique. That's the way to look at it.

"You're buying an item that is 200 years old. Now if there's a crash and raw materials like gold and silver diminish in value the antique will not in any way be affected," he says.

You should always insure antiques and it is advisable to reappraise the insurance value every five years.

Mr Jordan accepts that antiques can be a peculiar investment because you could be reluctant to cash in that investment. But "if you buy a new Chesterfield suite for £2,500, in 10 years' time you'd be lucky to get £500 for it. "Whereas if you spend £2,500 on a piece of antique furniture, it's going to be worth twice that much in eight or 10 years. It is nice to know that what you're sitting on is increasing in value."