How did you go wrong? The correct diameter of the stone was 6.7 mm but since the pavilion was enclosed it was impossible to measure the depth. This particular stone just happened to be a pancake (very flat). Perhaps the crown was of normal depth but again the pavilion was hidden. If the pavilion was this flat (way below 39 °), a very obvious fish-eye would be apparent. As discussed earlier, when a cutter varies from the critical 40.75 ° on the pavilion, the diamond's brilliance will suffer and a girdle reflection in the table will start to become more noticeable, depending on how far below the 40.75 ° the cutter has gone. In the case of a 6.7 mm diamond that only weighs 0.87 carat, the fish-eye should be extremely obvious.