Ultimately, the Naturcolor chart is similar to many other hair color charts, so reference the names of the hair colors, and use color swatches to determine which matches your hair tone. Avoid hair colors that are two shades lighter or darker than your current hair tone for the best results.
When searching for the appropriate color, keep a look out for the color codes, such as 4R or 7D, as they make it easier to track down specific brands. When checking for the appropriate color, use a strong light to get an accurate read. Dyes that are too dark or too light clash heavily with natural hair colors and result in odd color patches where the color soaks into the gray hair. Naturcolor is designed to dye gray hair differently than colored hair to appear more natural, and this effect is more prominent with colors that don't match the natural hair color.
If all else fails, consult a hair stylist on what the best Naturcolor shade is for a given hair color. Stylists have the training pick the right hair tones by eye, and a trained stylish can dye hair even when using a shade that varies greatly from the natural color.