When I went to paint shop to get the color for My truck it was only in My head I had to look thru a bunch of color books and when I found a color that was close I would ask what was in it as far as the colors I was looking for a blue grey or gun metal grey so when I found a combo that had just blue white and black I knew I had the color some where darker than others but it still made it easyer to pick it out . The color books are in sections it will go from yellow to green with all the different combos between also go out and set in the sun when Your looking, the guy in the shop said to and it made a big differance.
Good luck and take Your time ,Pete