Can these colours exist?

Sure! Colors can refer to a wide range of hues, shades, and tones, many of which can be represented and perceived. However, some colors exist only in theory or as a result of specific conditions. For example, some colors might be considered impossible due to the limits of human vision or the way colors are produced in nature. An example is "superblack," which absorbs almost all light and doesn't appear in a conventional spectrum. If you have specific colors in mind or want to describe a particular hue, feel free to share, and I can help explain whether they can exist or under what conditions they might be observed!