Cooper, who has been dating the ''It's Not Fair'' singer since July, splashed out the huge sum on the lavish vintage bangle after Allen fell in love with it on their trip to Italy.
"Lily spotted an amethyst and sapphire bracelet and said she loved it. The next day Sam sneaked off and bought it as a surprise," Contactmusic quoted a source as saying.
And the 44-year-old builder is not only spoiling Lily, 24, with expensive gifts, but is also encouraging her to pursue an acting career. "She would rock as an actress!" he said.