(IDEX Online) - Signet today said it had signed a deal to buy the online jeweler Blue Nile in a $360m all-cash deal.Signet, the world's largest retailer of diamond jewelry, said it was a strategic acquisition that would "accelerate efforts to expand its bridal offerings and grow its Accessible Luxury portfolio."Blue Nile claims to have over 650,00 diamonds available for sale, and says it has served more than 2.7 million customers to date. CEO Virginia C. Drosos said: "Blue Nile is a pioneer and innovator in online engagement rings and fine jewelry, providing a unique and highly desirable shopping experience for customers."Blue Nile, established in Seattle in 1999, and went public in 2004. It was bought privately by Bain Capital Private Equity and Bow Street LLC for $500m in 2016. Last month it revealed plans to rejoin the stock market, with a valuation of $873m.