"Dime piece" is primarily hip hop slang, and has been used in rap lyrics since the mid-1990s. Its exact origin is obscure, but it is more commonly used in the New York metropolitan area.
A dime piece is a beautiful woman, someone who is rated a 10 out of 10 in a ranking system for attractiveness. It may also be influenced by the unrelated term "time piece," or by similar terms for women, such as "piece of tail."
The term has seen some use on mainstream television shows such as "Psych," but it is primarily hip hop slang. For example, the fashion brand DimePiece designs urban street wear and features t-shirts emblazoned with African American slang.
The earliest usage of the term appears to date back to 1994, with a song released by rap artists Nice & Smooth, entitled "Do Whatcha Gotta." It was used in a spate of mid-1990s rap songs following this, including Tupac Shakur's "Whatz Ya Phone #," a track on his hugely popular album, "All Eyez On Me." The majority of artists who have used it are from the East Coast, particularly the New York City metropolitan area, indicating a possible New York City origin.