The world's No. 1 and No. 3 art-auction houses held competing Hong Kong sales this weekend, and found strong interest for top lots as Chinese collectors continued to buy expensive paintings and antiques in Asia's largest art hub.

But though sales remained strong, some categories—such as contemporary Chinese art—remain below their highs of spring 2011, the peak of the art-market boom in China.

"The cowboys have left town," said François Curiel, president for Christie's in Asia, alluding to the speculative buyers who sent prices skyrocketing in the past. He believes they're no longer bidding.