This looks dusty rose to me, which puts it in the medium range of color saturation, I think (correct me if I'm wrong, fabbers). So if you want a lengthening effect, I would go with medium-toned neutrals of any shade: medium wash denim, grays, olives, tans and browns--in other words, I would stay away from really dark navy and black, and perhaps even pure white. For my taste, I would want deeper color dyes watered down with white to match the color tone to that of the top. Just my two cents.