This cannot be done. Colors that exceed a predetermined NTSC composite limit are superimposed with those that do not on the Diamond display. They do cluster in the upper-left of the upper diamond and lower-left of the lower diamond but this is of little use. However, there are several alternatives for determining composite signal limit violations when producing in RGB or Y, Cb, Cr. You can connect a composite encoder and monitor the composite signal directly with a waveform monitor. Some signal correctors for the digital 4:2:2 format, such as the HP QA100, monitor and correct for composite signal limits. You can use the WFM601M, which in addition to the Diamond display has a new Arrowhead display, to explicitly show the composite signal gamut with over limit values that you can set from 100 to 133 IRE. It also includes threshold detectors and picture monitor indication of NTSC/PAL composite signal limit violations.