You may have heard of these wavelengths shortened to ROYGBIV, which stands for red, orange, yellow, green, blue, indigo ... to see if the inks separate. So, is black a color? Each of the colored ...

The dial has a uniquely Japanese color called “Ao-zumi” (literally blue-black). This shade is a deep-blue variant of the black sumi ink traditionally used in Japanese calligraphy and painting.