Instinct is key to choosing the best, said local oenophile Simon Tam, one of two dozen judges at this year's International Wine Challenge of Asia, where 900 vintages are in competition. The judges will gather at Cyberport today for the final rounds of the three-day competition. Wines are marked using internationally recognised benchmarks for taste, aroma and other characteristics. 'It all sounds very technical,' said Mr Tam. 'But when you know what you're doing, it becomes instinctive.' Mr Tam, who was born in Hong Kong and raised in Australia, runs his own wine-consulting service. He has been judging wines in competitions for 11 years. For this event, organised by the Wine Institute of Asia, he joins 18 judges from Hong Kong and six from overseas. Vintages from Australia, New Zealand, the mainland, Chile, France and a number of other countries are in competition for a gold, silver or bronze rating, or a seal of approval. To ensure fairness, at least 10 judges try each wine, its label concealed. With 900 wines included, a judge must taste between 150 to 200 glasses a day, but it goes by quickly, Mr Tam said. He demonstrated by examining the colour of one glass' contents, sniffing the wine, then swirling it around in his mouth - all in less than 10 seconds. Mr Tam said he evaluates wines on, among other things, whether they have pure fruit flavours and a moderate use of oak flavouring, which comes from the barrel in which they are stored before bottling. The downside is that judges cannot swallow any of the wine, and it also leaves tongues purple-blue. Wines from the mainland are growing in quality Mr Tam said. Some of his favourite brands from north of the border are Grace Vineyard, Hua Dong and Dynasty. 'It would be nice to see a highly decorated Chinese wine,' he said. 'It will happen inevitably.'