Tiffany & Co. posted a 62-per-cent drop in quarterly earnings yesterday, worse than Wall Street had expected, as jewellery sales languished in the recession. The upscale retailer said sales trends had improved slightly in May, but not enough to boost its weak full-year outlook as rough economic conditions persist. Tiffany, which has already said that its U.S. sales decline would ease a little in the second half of the year, saw its New York flagship store suffer the most with a 42-per-cent decline in revenue. Sales of jewellery over $50,000 (U.S.) faced the steepest drop, a company spokesman said. TIF (NYSE) closed at $28.37, up 24 cents.