What does it take for a coral to qualify as a rainbow colored piece? Since corals with two distinct colors are so commonplace these days, should the minimum qualification be three colors? How about four colors? There are no real guidelines as to the naming of corals, and with everyone trying to have that eye-catching name, you might end up looking at a rainbow coral with only a few distinguishable colors. And with creative lighting and photo enhancing, that three color coral might appear to have many more. So, be careful with the naming hype and buy corals that you truly enjoy looking at.