Do you know who painted it ? What type of paint was used ? Brand,type, lacquer, enamel, base and clear coat, etc... Any top quality paint mfg. has the technology to match color. You will need a sample, best taken from a door jamb or similar area protcted from uv sunlight. Depending on the color and paint type and exposure, some colors change quite a bit like yellows that turn to a cream color. Some are more forgiving. As AlleyoopMgv says, you may end up having to shoot and blend the area around the cap to get a close match. I would check with the areas top rated paint and body shop and have them show you the options and samples of their work.