Among my favorite creations is a simple Amethyst with a blue light.  As the glow fades on and off, it shows the beauty of the crystal, then the curiosity of the glow, alternating between states. 

The more you look, the more you see there is nothing simple about it.

Two replaceable 312 batteries keep this lit for weeks, and the necklace cord is adjustable.  Every Firefly is made in my studio and comes with free shipping and extra batteries.