Color

adjust-color($color, [$red], [$green], [$blue], [$hue], [$saturation], [$lightness], [$alpha]) Increases or decreases one or more components of a color.
scale-color($color, [$red], [$green], [$blue], [$saturation], [$lightness], [$alpha]) Fluidly scales one or more properties of a color.
change-color($color, [$red], [$green], [$blue], [$hue], [$saturation], [$lightness], [$alpha]) Changes one or more properties of a color.
ie-hex-str($color) Converts a color into the format understood by IE filters.
Note the difference between change-color() and adjust-color().
$a: #cccccc;
div {
   background: change-color($a,$blue:1);
   color: adjust-color($a,$blue:1);
   border: 1px solid ie-hex-str($a);
}

div {
  background: #cccc01;
  color: #cccccd;
  border: 1px solid #FFCCCCCC;
}