Returns a value that indicates how dark or light a one-color gradient fill is. A value of 0 (zero) means that black is mixed in with the shape's foreground color to form the gradient; a value of 1 means that white is mixed in; and values between 0 and 1 mean that a darker or lighter shade of the foreground color is mixed in. Read-only Single.
This property is read-only. Use the OneColorGradient method to set the gradient degree for the fill.