Color becomes crucial for clients as they age. The tell-tale sign? Those pesky gray strands. And as these clients are your most loyal—often visiting your chair every five to six weeks—it's important to treat them right. To try out the new Schwarzkopf Professional IGORA ROYAL ABSOLUTES, Guy Tang tested it on a very special client—his mother! Not only did Guy "Tang" her hair, he also gave her a modern cut to bring out the color. "You have to build the house before you paint it," says Guy. "You need to create the foundation before you color." And…