The whitelabel brand does not assume much colour. White and black, or a mix of the two, is common as a placeholder. Jade and crimson are often used as a success/error placeholder colour.
Tones (colours with modified brightness using the HSB colour space) can be used to produce a broad spectrum of lighter and darker variations of palette colours for creating scale and depth to your designs. To reduce our number of colour combinations not all colours may be toned, but mixes of black/white may be used instead.