I keep seeing auctions where the word Fiesta is prominently displayed in the title, yet the item itself is a piece of the Harlequin line.  Here's some history to help you understand why this is NOT Fiesta ware.

Harlequin was designed by the same company that makes Fiesta, Homer Laughlin, and the same designer, Frederick Rhead.  It was created to sell exclusively at Woolworth's and was sold from 1938 to 1964.  It uses many of the colors that are used on Fiesta dishes, but the design is different.  It has rings around the plates, for example, but they are towards the middle.  The old Harlequin dishes are usually NOT marked at all.

In 1979, Harlequin was reintroduced to commemorate the 100th anniversary of Woolworth's.  These dishes ARE marked Homer Laughlin, so if you see these they're not vintage at all.

A wonderful resource is a book called FIESTA by Bob and Sharon Huxford.  This book saved me from making an expensive mistake on an auction of mislabeled 1979 Harlequin.  Do your research and if you want Fiesta, don't buy Harlequin!