Here's something most buyers don't realize: despite the name, Rainbow Moonstone isn't chemically the same stone as classic white Moonstone.
It's actually a variety of labradorite that happens to show the same shimmering optical effect — light bouncing off internal layers to produce that floating blue flash — which is why the trade settled on calling it "Rainbow Moonstone" instead of introducing a whole new name.
The visual effect itself is called adularescence, and it's the reason a plain-looking cabochon can suddenly light up with electric blue when you tilt it under a lamp.
That flash is entirely angle-dependent, which is part of what makes buying it in person (or from good photos) worth the extra look — a cabochon that looks quietly milky from one side can flare into a full blue sheen the moment it catches light correctly.
Sourced from India, this lot is cut into mixed shapes with a flat back, so the flash sits centered wherever the cutter found the strongest angle in the rough. In crystal-healing circles, Moonstone is tied to the moon's cycles, feminine energy, and emotional balance — it's also June's birthstone, which keeps steady demand for it in gift-oriented jewelry.