Stars of the U.S. hip-hop music industry are becoming proud owners of unique new watches by top luxury-watch brands.

Hip-hop artist and record-business entrepreneur Jay-Z and Swiss luxury watchmaker Audemars Piguet in April unveiled a limited-edition watch (100) to mark his 10th anniversary in the music business. The watch—a special version of the brand’s Royal Oak Offshore chronograph—has a small “10” in diamonds on the dial; comes in stainless steel, rose gold, and platinum; comes with a 40-gigabyte iPod uploaded with Jay-Z’s albums; and retails for $23,500 to $69,500. Jay-Z—a watch collector and longtime fan of the brand—was actively involved in the design. The project took two years. François-Henry Bennahmias, president of Audemars Piguet North America, says there will be more limited-edition projects with celebrities in sports and entertainment this year, and that, as with the Jay-Z watch, some proceeds will go to charity.

Meanwhile, hip-hop star Usher recently got a one-of-a-kind $85,000 Tiret New York timepiece, with 1,106 diamonds (9.5 cts.) on the bezel and his face—made of natural fancy diamonds set on a background of white diamonds—on the dial. The watch, which has two time zones, two dates, and two chronographs, took more than seven months to make.

Usher ordered the watch after he saw fellow hip-hop star Kanye West wearing a similar one, given to him by Tiret New York company owner and hip-hop music mogul Damon Dash after West was nominated for four MTV video music awards last summer.

Usher’s watch will be exhibited at the Natural History Museum in London during the world’s biggest diamonds exhibition, starting in July and running thorough February 2006.