Pink stones such as pink sapphire, pink tourmaline and pink amethyst are in demand, along with black diamonds. 'Black diamonds only cost about a third of the price of white diamonds,' Ms Ma said. Another trend is pairing pink or red stones with pink gold settings.

Supplies of most gemstones have been good, and prices have increased slightly since last year. 'For semi-precious stones, prices have gone up about 5 per cent,' Ms Ma said.

Less costly coloured gemstones continue to appeal to women in their 20s and 30s. 'They want colour and a design that matches their personality and their outfits, rather than expensive stones,' she said.

Many of the company's customers prefer large gemstones of 10 carats or more, combined with a few small diamonds.

At Nazim Brothers, one of Hong Kong's largest gemstone dealers, blue and pink sapphires, pink tourmaline, aquamarine and peridot are all doing well this year. Company director Abdul Rahman said: 'Rubies are picking up. In the past two years, people wanted less of them, but now they want more.'

He said sales of precious stones had remained steady, at the same level as last year, and the company's best-sellers were medium-quality stones of three to five carats in round or oval cuts.

'Younger people tend to want semi-precious stones and older people want precious,' said Mr Rahman, who added that Europeans favoured higher-quality, higher-priced stones, while Americans looked for the most competitive prices.

Spinel, aquamarine and sapphires were among the higher-tier coloured stones, with yellow sapphires and peridot in the mid-price range, he said.