White diamonds remain in demand among conservative Hong Kong buyers despite a recent dip in the global market, but auctioneers are also offering a wide variety of other stones to meet the more adventurous tastes of the mainland's nouveau riche.
Jadeite, coloured diamonds and other gemstones are being brought in by auction houses to test the market.
"Mainland collectors have more diversified tastes," Stewart Young, director of the jewellery department at the Hong Kong-based Tiancheng International Auctioneer, said.
In jadeite, for example, Hong Kong collectors preferred a translucent green tone.
But now the auction house, which is holding a pre-sale preview in its Central showroom, offers hues from dark green to clear.
"[Mainlanders] are willing to spend on anything from the very dark green 'old-mine' jadeite to clear, icy jadeite and even red jadeite," he said.
The Rapaport Diamond Index shows prices for one-carat diamonds in April fell 0.5 per cent, while prices for three-carat diamonds dropped 0.6 per cent after a rise in the first quarter.
But the index also cited data from the Diamond Federation of Hong Kong indicating growth.
It showed polished imports up 11 per cent to US$4.39 billion and polished exports up by 18 per cent to US$3.29 billion.
In April, Sotheby's realised more than US$106.6 million at its Hong Kong spring auction compared to US$61.4 million in the same sale last year.
While jadeite, unlike diamonds, does not have a standard price, mainland clients' growing interest in the stone is helping attract some hefty prices.
In 2012, Tiancheng sold a jadeite bead necklace for US$13.6 million, a record at the time.
Last month in Hong Kong Sotheby's sold the Hutton-Mdivani jadeite bead necklace with a Cartier diamond and ruby clasp for US$27.44 million, setting a world record for jadeite jewellery.
Buyers are after large, high-quality coloured diamonds for which price per carat can reach US$1 million.
Earlier this month in Geneva, Christie's sold a 13.22-carat flawless fancy vivid blue diamond for more than US$23.7 million, achieving a record price per carat at US$1.79 million.
Bonhams Asia's director of jewellery Graeme Thompson said mainland collectors preferred contemporary and bold pieces with large stones.
"They don't mind the amount of money they spend, but they want pieces that are value for money," he said.
At Tiancheng's June 8 auction, more than 70 of 360 lots are to be sold at no reserve. Christie's will hold its spring jewellery auction on Tuesday at the Convention and Exhibition Centre, with more than 300 lots with a pre-sale estimate of HK$800 million.