We report on the results of a visual experiment using forty-nine 3 step color series supplied by the Federal Institute for Materials Research and Testing (BAM, Berlin), which were assessed 3 times under a D65 source by a panel of 20 observers with non-defective color vision. This experiment tries to contribute to current CIE TC 1-63 work, analyzing the performance of 7 advanced color-difference formulas (CIELAB, CIE94, CIEDE2000, DIN99d, CAM02-LCD, CAM02-UCS, and OSA-GP) for color pairs with large color differences in a very wide range: 10-95 CIELAB units. After earlier results, boxplot analyses detected that some answers from specific observers (9.2% of the whole results) were outliers. These answers were removed, and a total of 2669 visual assessments were managed. In overall the CIELAB formula provided the best predictions of our visual results (53.5 STRESS units), followed by the CAM02-LCD formula, the average inter-observer accuracy in our experiment being 43.6 STRESS units. These STRESS values are greater than those usually found in experiments involving small-moderate color differences, like the ones conducting to the proposal of the CIEDE2000 formula.