A display device comprises a layer of display cells separated from each other by partition walls and filled with a display fluid. The display of the invention is divided into a non-watermark area and a watermark area, the latter forming a watermark. The watermark aims to protect against counterfeiting or to be used for decoration purposes. The watermark is visible at certain viewing angles and/or under certain lighting conditions and it does not interfere with displaying of the regular images. For example, each of the display cells in the watermark area may have a different size from each of the display cells in the non-watermark area. Alternatively, the watermark area differs from the non-watermark area in at least one parameter selected from partition wall height, partition wall width and the shape of each display cell, and the watermark area is divided into at least two parts having differing values of the parameter.