Violet and Light Green
In color perception theory, at the color wheel there's a division that differentiates warm and cold colors. This division is the one set by violet and light green: above this line the warm and below the cold. Violet and light green have as an attribute that when they are in a warm composition they turn warm and when they are in a cold composition they became cold colors. This lack of definition makes them not warm or cold colors.
The colors halfway between these warm and cool extremes, such as yellow-green and red-violet, are fairly neutral; they seem neither very warm nor very cool. The warm and cool qualities of color at this points are very subtle.
From Ich werde ein perfekter Künstler. Bd. 2. by John H. Miller, Sonja Steiner-Welz