There was an old article in Chip Chat were Doug did the research and established that the $1's were never used in Las Vegas (Just Stockton), the $25's were only used in Las Vegas (Never in Stockton), and the $5's were actually used in both locations (which is why they are all worn smooth.)

I have seen lots of California chips being sold as Las Vegas, including the Matty's and, recently, some chips from the Western Club in Gardena.