Nicole Richie designed her own engagement ring.

The TV star - who revealed her betrothal to Good Charlotte rocker Joel Madden during an appearance on 'The Late Show With David Letterman' this week - worked with renowned celebrity jeweller Neil Lane on the band, which sports a flawless four carat, round diamond.

Lane told People magazine: "We designed it together. Nicole was lovely and wonderful to work with on it! She wanted a beautiful, special ring and wanted to be intimately involved in the design."

The jeweller - who has previously created pieces for a host of stars, including Gwyneth Paltrow, Madonna, Nicole Kidman and Charlize Theron - also revealed Joel let his wife-to-be have complete control over the design.

He added: "Joel just wanted her to have her dream ring."

It was on Monday (15.02.10) that Nicole, 28, confirmed she is engaged to Joel - with whom she has two children, daughter Harlow, two, and five-month-old son Sparrow.

Joel, 30, later revealed his joy with a posting on his twitter page.

He tweeted: "Yep. I'm engaged. Very happy. Yeah we've been engaged for a while so you're all kind of late on that. But Thanks for the hooplah all the same. (sic)"

The couple are reportedly planning to marry this summer.