I should know as I'm a painter. Pearl is powder. You add this to a clear or can mix straight into a colour to get the look. Although it's not metallic as you would say but it's give the colour a metallic look. Mica is the same deal. Mica is pearl. There are lots of different ways to go about mixing mica/pearl to get a different look. Colour shifts are 2-3-4-5 etc layer pearls. For instance you paint 1 layer red pear, 1 layer green pearl, 1 layer blue pearl to have a 3 layer pearl colour shift. Colour shifts are when to see 2 ir more colours when looking at different angles. Although it can be a lot more technical than this.