Have you ever witness the Aurora Borealis in the Norwegian Artic? Perhaps you may have come across it in video clips and still life photography.
The billowing clouds of bluish, whitish and very light greenish color have a shimmering aurora on their own. This type of ever shifting light that seems to float on the atmosphere is called Adularescence.
Moonstone has the property of Adularescence. The billowy bluish light on moonstone is caused by the crystallization of alternating layers within the gems that cause the scattering of light. Thus, when light strikes the surface of a moonstone cabochon, instead of being reflected in one direction or being refracted within the gemstone, the light scatters in all direction.
This ‘milky’ or ‘opalescence’ that shimmers on its surface has made moonstone highly attractive. The adularescence shimmering color on the surface of a moonstone is determined by the thickness or the thinness of the intergrown layers. Thin layers of intergrowth produce the most bluish adularescence while thicker layers produce a whitish adularescence.
When the layers are properly oriented, light striking the surface can be focused into a cat’s eye, and the cabochon is called a moonstone cat’s eye. Rainbow moonstones are those with multiple hues.
Moonstone occurs in a variety of colors; colorless, whitish, greyish blue, bluish green yellowish green or very light orange. The most desirable moonstone is usually translucent with bluish adularescence.
Although adularescence and labradorescence are quite closely related, the means of light scattering from within the gem and from its surface are different. Adularescence is internal while Labradorescence is only found on the surface of the gems.