Returns whether or not the color is stored in Excel's default color palette. For .xlsx files, returns whether the color has been retrieved from the legacy palette. The only way to retrieve colors from the legacy palette is by using the Palette.SetColorAt or Palette.GetColorAt methods.

public boolean IsPaletteColor{ get; }
Public ReadOnly Property IsPaletteColor() As Boolean
bool paletteColor = clr.IsPaletteColor;
Dim paletteColor As Boolean = clr.IsPaletteColor