That's exactly what Rocky's coat does, except he gets gold instead of red:)
Becky
Have you ever body clipped him? I bet he'd be hard to get to come out good, he'd darken in those patches where the root is dark. Pony would turn nearly black if I clipped her, her hair starts out black at the root and lightens.
Bay has a ~really~ impossible hair to clip. I'm glad I never showed him. His hairs are actually three colors. around his face they start out black, turn yellow in the middle of the hair, and then get redder, so if you clip him, he comes out three different colors, and it looks really funny. Sometimes in spring I'll clip his neck and girth area in a modified hunter clip, to get rid of the hair, but it looks funny, the clipped areas look a starkly different yellow. There's a name for that... when the hairs themselves vary in color from root to end, but I don't remember what it is.