ZURICH (Reuters) -Cartier jewellery owner Richemont painted a mixed picture of the luxury sector in its latest results on Thursday, reporting a sales decline in Europe but a big increase in China. The Swiss-based company said sales in constant currencies, which remove foreign exchange fluctuations, fell 3% in Europe as higher sales to Chinese tourists and domestic customers failed to compensate for lower spending by travellers generally, particularly from the United States. Sales increased by 25% in China, including Hong Kong and Macau, the company said, countering concerns about a slowdown in the region as its economy cools.