Arlene,

what I learned in my research - there are two ways to change grout color.

grout stain (dye) - like wood stain, soaks into the grout but is limited to only changing color a shade or two.

grout colorant - topical application (like a thick paint over wood). apparently you can get a greater change in colors but I have no idea how this would look & how long it would last. Maybe this is what this company is using. Gives you some questions to ask though.

Believe it or not, there is a message forum dedicated to tile, stone & grout questions. lol johnbridge.com