The invention relates to a method of controlling the quality of blocks that are produced front face-up in a mold, and verifying the accuracy of the production of such blocks, to ensure that the blocks are manufactured with consistent quality and minimal block-to-block variability. Measurement locations are formed on the front faces of predetermined blocks. By measuring the distances between the measurement locations and the rear faces and comparing with a target distance, any variation provides an indication that the blocks are not being properly formed. The process variables, such as the alignment of the compression head and/or the pressure plates to the mold, can then be adjusted accordingly.