The Borelli Marble and Granite company explains that thousands of colors exist. The color range is from white to black, with all the colors of the spectrum in between. Inside each color, different shades, textures and tints exist. For example, inside the red color is African Juparana. This granite has large areas of sand-colored rock, interspersed with red streaks. It has almost a wood-grained look. At the dark end of the range, Capao Bonito has a deep burgundy hue, with red and black areas interlaced.
Color interspersion is a unique feature of granite. since its a natural stone, it is not one solid color. Rather, colors are interspersed inside the stone. This adds visual interest, since flecks of multicolors are visible. For example, in Asa Branca white granite from Brazil, areas of black specks intersperse the white.
In the areas of interspersion, color density varies. In a red granite, large areas of white may be visible. Conversely, in another red granite, large areas of red may be visible, with only a few areas of white specks. Its up to you to find the right color density for the area you are designing. The only way to choose correctly is to look at color samples, and pick the density you want.
Besides the color density, hue density has to be looked into. For example in Amarelo Tombas, the hues are deep red, black and with a few white flecks. In an Argentine Mahogany, the hue density of the red and black areas is lighter. The color density is the same in both cases, but the hues of the darker and lighter areas change. Again, look at granite samples to pick the one that's right for your design.