Whether you have a single old bottle of wine at home or you're a finewine aficionado with a vast collection, you may wonder how much your wine is worth.

Mr Christopher Burr, international head of the wine department at Christie's in London, says much of the fun of collecting wine is "watching the wine develop and trying it at different periods".

When buying good wine, he encourages collectors to buy two cases. The first one would be consumed at different stages of its development: "It's like children really. I mean kids are great when they're babies. They're lots of fun. And then they become spotty adolescents and perhaps not so interesting. And then as they get to their 20s they become really good fun again. And then they mature into sensible, attractive people, hopefully. So a wine is not actually much different. It goes through these life periods."

You could keep the second case if it turns out to be very good. Many clients put certain wines back into the market "by which stage the price has hopefully improved if they get their timing right". But the price doesn't always improve. "There are peaks and troughs like any market. But if they get the timing right they can put it in the market and then reinvest what they've made in some younger wines and continue the whole process," he says. Wine is a living foodstuff. Sometimes its life cycle is extremely long and sometimes it is not. It depends on the quality of the wine and the way it has been stored. A top red wine can last 100 years. But probably it is at its best after 25 or 30 years. If you buy it young and sell it at its best you could make money on it.

Record prices achieved for wine include a bottle of Lafite 1787 which fetched £105,000 sterling in 1985; £71,500 for a Mouton Rothschild 1945 in 1997; £68,200 for a bottle of Cheval Blanc 1947 in 1997; and a bottle of Yquem 1784 which achieved £36,000 in 1986.

So how might a reader know if a bottle or collection were valuable? "What they do is they pick up the phone to us and ask someone in the wine department. We give them a free estimate over the phone, on the basis of the label - subject to the condition and how it has been stored."

Storage conditions are vital. These should be cold and damp, "and if it's in Ireland, it probably is", he says. Other considerations include if it is from a famous house or name, such as Lafite. How long have you had it? What does the cork look like - is it seeping? Is it a good vintage, that is, was the year it was produced a good one for that wine? "The only way people would know that, unless they have a degree of wine knowledge, is if they buy books that are inexpensive, such as the Hugh Johnson pocket guide to wine," he says.

Many people in Ireland are highly educated about wine. According to Ms Jean Smullen, administrator of the Wine Development Board of Ireland, there is great interest by Irish consumers in the courses in wine organised by the wine board. As many as 1,600 Irish wine enthusiasts and collectors have attended third-level certificate and diploma courses at 27 locations around the State already this year. Those interested in wine courses commencing next January can contact the Wine Development Board of Ireland by dialing: 01 280 4666.

Readers are welcome to ring Christie's wine department for a free wine valuation. Telephone: 0044 171 389 2723.