* "G. Hair" brand: This is a brand of Brazilian keratin treatment, which doesn't change your hair color. However, since keratin treatments are often done to make hair smoother and shinier, people might use it on hair of any color, so it could be any color.
* Hair color with a "G" name: The color is probably gray, green, or gold.
Can you provide more context? If you're seeing something specific that you need help with, please let me know!