According to their publicity materials, Almay Smart Shade foundation changes its color to match your skin.
How does this work?
Surely it’s not just an updated version of those “mood lipsticks” I used to buy in junior high that changed color from green to hot pink when warm, supposedly based on your “body chemistry”?
The only thing I can think of is if it had some sort of clear beads or prisms in it (on a microscopic level) and the rest of the makeup was somewhat translucent (but already tinted towards the color of skin). Then I suppose it could pick up the color of your skin and reflect it into the rest of the makeup and out to the ‘viewer.’ Photoshop’s “Healing Brush” comes to mind.