Yes, moonstone is a real precious gem. When it comes to determining whether a moonstone is genuine or not, one characteristic to look for is its adularescence, which is a special visual effect that produces a hazy, bluish radiance or glow on the surface of the gemstone.
To check for this effect, you can place the moonstone under a bright artificial light source and observe it from above. If you can see a blue or white sheen emanating from the stone, then it is likely that the moonstone is authentic.
And if you do not have the time to do such a test, simply buy from a reputed brand like Beads of Cambay to ensure you get nothing but real moonstone beads.