Abstract: In recent years, colour diamond attracts much market attention. Pink diamond and blue diamond are important varieties of colour diamond, and their prices have repeatedly set records for jewelry auctions. This research focuses on blue diamond and pink diamond in the international auction market. Through descriptive statistics and analysis, it comprehensively introduces the blue diamond and pink diamond in the global auction market and explores the impact of quality factors on their prices. This study found that the prices of pink diamond and blue diamond increase steadily. The colour diamond auction market in China is developing rapidly and well. Jewelry auctions in Hong Kong and Geneva deserve more attention. Sotheby's and Christie's dominate the pink diamond and blue diamond auction market. Colour is the most important factor influencing the price of pink diamond and blue diamond, and its impact is significantly greater than that of carat weight. Generally, the round shape has the greatest positive impact on diamond price. The impact of clarity grades and cuts on auction prices is easily disturbed by other factors. This research can provide a reference for bidders, collectors, etc. to understand and master the auction market of pink diamond and blue diamond.