Schiller

labradorescence in polished labradorite

 

 

Schiller which comes from the German word for 'twinkle' is an optical phenomenon that's also known as adularescence.  It's only produced as light interacts with the internal microstructures in a mineral and is not a property of the stone itself.

When schiller is visible in the mineral labradorite the effect tends to be known as labradorescence because labradorite is renowned for being iridescent.