The reflection of the sun
The rainbow moonstone
is actually not a moonstone, but a kind of labradorite (plagioclase feldspar). Its similarity to the moonstone (potassium feldspar) is how it gets its more widely known nickname: rainbow moonstone. What labradorite and moonstone have in common, is that they come from the feldspar family. A mineral that makes up more than half of our earth's crust.
Our rainbow moonstone comes from Sri Lanka and Tanzania. It then gets its wonderful cabochon cut in India before it is turned into jewelry in our smithy in Bali.