A couple of days ago I sat with a friend of mine late into the night doing some serious wine tasting. The climax of the evening was sharing a bottle of Chateau Petrus 1989, a wine which ranks at the very top end of the galaxy of wines. We had Robert Parker's book open in front of us and read his detailed description, which culminated in his marking this wine 100 out of 100. Now in any language that's perfection, a mark he also gives to the 1990 from the same Chateau, and this led to a discussion on rating wine.

Tastes are profoundly personal things, but it's none the less true that most of us can recognise excellence when we're confronted with it. If there are debates to be had, they centre on whether a score might be 98, 99 or the perfect 100. Where a book like Robert Parker's comes into its own is in guiding a reader through a labyrinth of tastes and vintages like that of the great Bordeaux Chateaus. It's a rarefied pastime; wines like these cost more money than many people earn in a month, so it's given to few to explore these realms.

But another thought occurred; there's a circularity here. The first way of ranking a wine is clearly by taste, the second is the confirmation of greatness given by its market value. But these two things get intertwined when a wine is prominently reviewed by a respected authority like Robert Parker. A recommendation from his 'Wine Spectator' can have a significant upward impact on a wine's market value, which further confirms the wine's greatness. It's a loop that's hard to avoid.

But for the majority of us great vintages from great Chateaus are more vicarious than actual experiences. Thirty years ago they were affordable, today international pressure on the markets has ensured that they are not. But there are still great wines to be found, and that's perhaps where the job of a wine journalist comes into play. By tasting many wines from many suppliers we can whittle down the choices a little, using our own personal prejudices and idiosyncratic palates. There are books, too, that can help the consumer. My colleague Mary Dowey of the Irish Times has just published a book entitled 'Best Wines', which is a comprehensive listing of wines available in Ireland. There are tasting notes, the stockists are listed for each wine and it's published by Town House, retailing at around 13 euros. Martin Moran, an Irish Master of Wine, has published 'Wine Republic', which rates not only the wines, but also the retail outlets. It's informative and well-researched and is published by Passion Publishing at 15 euros.

Wine of the Week

Don Melchor 1997, Private Reserve, Concha y Toro

Because South America and this wine in particular have yet to achieve high international status, this wine, although expensive, can hold its own against some of the world's finest at a fraction of their cost. Harvested by hand and aged for a year in French oak, it's elegant and complex with hints of vanilla.

Available Redmonds, McCabe's, Bennett's, Kelly's of Artane and O'Brien's. RRP 32.50 euros