My usual test is a cuneiform replica or a fossil. Today this dome had a full test with the tablet and my Nikon D650 (100ASA, 1/10s F10, jpg, no white balance calibration).
This replica is very useful and is of the Sumerian period (2600 BCE). It is 8cm x 7.5cm and came from the Sumerian city of Shuruppak. It describes the sale of a house and names two witnesses. The original is in the Louvre Museum