Red, Green, Blue, Transparency
Example = 1 0 0 0.5: //Would mean your particle at this point is Red, and half transparent.
Example2 = 1 1 1 1; //Would mean you particle would be White and not transparent.
You can combine colors as well to make specific colors of course
1 1 0 1 = yellow
0 1 1 1 = cyan
1 0 1 1 = purple