Chinese consumers can buy designer products in the United States through the online retailer.

"We want to help designers gain popularity in China and meet the growing demands of our consumers by offering the world's leading fashions," said Lang Xueyue, vice-president of the company.

Fifth Avenue Globe, another Chinese online luxury retailer, said sales of niche brands accounted for half of its turnover in 2012, up from 20-30 percent previously.

Despite a slowdown in sales across many other retail sectors, brand sales have held up strongly in China, say experts.

Sales of the Italian label Bottega Veneta surged 41.5 percent year-on-year in 2012 in China, where it operates 41 stores, according to Kering Group's annual report, against an overall 17.6 percent rise in Kering's luxury goods sales in China.

China has already become the third-largest market for Yves Saint Laurent, a French high-end fashion brand.

Growing sales of niche luxury goods are yet to have any significant effect on the larger luxury brands in China, given their relatively small scale.

However, Zhou Ting, director of the Fortune Character Research Center, said as their sales grow, the bigger names will start to take notice.

It will be more difficult for all the luxury brands to earn money from China's market in future, Zhou said, although the market will still lead global growth. "The market will enjoy healthy development, with many choices for consumers," she added.