Rainbow Moonstone Mini Gold-Fill Pendant
The stone is an Rainbow Moonstone.
Rainbow Moonstones are a type of stone that shifts color as the light hits it, at some angles they may show certain colors, but at other angles they may appear white. (see video).
The wire is gold-fill. The cord necklace is included, it is nylon and is adjustable roughly 18"-20". The last photo shows back of the pendant, it is next to a ruler for size comparison.