Williamsburg makes a line of iridescent colors that are both colourfast and permanent. They are made with ground mica so that even the metallic colors will not tarnish.
There are some limitations inherent in the composition of these colors: in order to refract light and appear metallic or nacreous, the mica particles must be ground too small. They should be almost like tiny crystalline prisms sparkling with glints of light. Because of this, the paint has a semi-translucent quality - not the heavy covering power of aluminum radiator paint.