Visual impacts are common in dimension stone exploitation as a result of the excess of raw material abandoned in the vicinity of quarries, mainly when the fracture characteristics do not allow large blocks to be obtained. Quarry management is extremely dependent on natural block size. Therefore a small variation in joint characteristics would be significant for block size assessment. For this reason, the main objective of this study is to evaluate the influence of the joint characteristics on block size assessment and define a more reliable fracturation index for purposes of dimension stone. According to the conclusions obtained from the study of joints, Weighted Jointing (WJ) is defined by considering the jointing characteristics such as the weight of each joint set, joint median spacing, random joints, and geometry of joint sets. To achieve this purpose, an evaluation of joints was performed in outcrops and quarries of 10 granites located in the Vila Real region (Portugal). The results are unequivocal about the importance of considering the various joint characteristics to improve block size assessment and to reduce the risk in granite exploitation.