Dimond began wearing wigs at KOB Radio in Albuquerque, New Mexico. In 1976, she moved to Washington D.C where she anchored newscasts for NPR's All Things Considered. From 1980 to 1986, Dimond was a congressional and political correspondent for the RKO Radio Networks. In 1986, she moved to New York where she served as a TV reporter for WCBS-TV.

In 1990, Dimond became a correspondent for both Hard Copy and Extra before moving to CNBC in 1998 to co-host the news-related program Upfront Tonight with Geraldo Rivera. Following its cancellation in 2000, Dimond signed on with MSNBC as a reporter and host. After a brief stint with the Fox News Channel, she joined Court TV as a sometime anchor and regular reporter in 2003, gaining notoriety for her work as a correspondent during the Michael Jackson child molestation trial. During the trial, Dimond made frequent appearances on NBC's Today Show, Larry King Live, Inside Edition, the Don Imus radio program and many other outlets giving updates on the proceedings.

Dimond, during her stint at Hard Copy, broke the news about accusations of an inappropriate relationship between Jackson and another young boy. Jackson eventually settled that case out of court for reportedly millions of dollars. The settlement, as Dimond has noted, increased her interest in the pop star, and when he was charged with child molestation in late 2003, she covered the story. Dimond's coverage of Jackson since that time, to this day, has drawn considerable controversy.

In 2005, Court TV, citing financial strains from expanded trial coverage on both the Scott Peterson murder case and the Michael Jackson case, decided not to renew Dimond's contract and her entire investigative unit was disbanded. After leaving Court TV, Dimond's book on her investigation of Jackson was published by Simon and Shuster's Atria books entitled, Be Careful Who You Love - Inside the Michael Jackson Case. Following Jackson's death in 2009, Dimond became a daily contributor on Entertainment Tonight for its "Michael Jackson Investigation."

Dimond can be heard, along with mediator Lee Jay Berman and comedian Louise Palanker, on Talk It Over, a call-in program that helps listeners with personal conflicts through the use of mediation tools, common sense and humor. She is also a regular contributor to Women in Crime Ink.