Friday, February 17, 2017

Moonstone v. Rainbow Moonstone---Same or Different Gemstone?

Moonstone is a very popular gemstone.  Rainbow Moonstone is also extremely popular, but are they the same gem?  How are they different?  Is Rainbow Moonstone just a variety of Moonstone? What about other colors of Moonstone, like peach, pink, or grey?   It's very confusing, even for jewelers and mineral collectors. Here's some information I've gathered about these gemstones---I hope this is helpful!

The minerals of the Feldspar group are the most widespread minerals around the world and make up 60% of the earth's crust. Basically, long story short, feldspars are a beautiful and complex gem family that includes Moonstone, Labradorite, Sunstone, Sanidine, and others. Moonstone is a variety of the feldspar group mineral orthoclase and is actually made of two minerals, orthoclase and albite. During formation, orthoclase and albite separate into two stacked, alternating layers. When light falls between these thin layers, it is scattered into many directions, producing the phenomenon called "adularescence." Adularescence is the light that appears to move across a gem, giving it a glowing appearance.  This glowing light moves as you move the gem.   This glowing feature can be a bright or subtle blue (deep or pale), white, grey, or even a "catseye" appearance:

Moonstone with "Catseye"

Moonstones are found in an array of colors---peach, orange, yellow, green, grey, black, blue---some with a white adularescence (like the moon) or with blue adularescence (like moonlight on water). Here is a screenshot of a chart showing the different colors of Moonstone---please visit HERE to see the original chart, and the pictures of each gem can be enlarged, plus more information on Moonstone:

As the chart shows, there's a wide array of each of the colors of orthoclase Moonstone.  Here is another example of some of the colors of moonstones which exhibit a very slight glow that to me looks a little like mother-of-pearl:
Colors of Moonstone

Other feldspar minerals can also show adularescence, especially Labradorite, which is found in Labrador, Canada.  Another form of Labradorite that is found in Madagascar is called Rainbow Moonstone.

Rainbow Moonstones
This gem has a multicolored adularescence over a light or transparent body color.  It can also have a singular deep blue adularescence.    It’s known with the trade name "Rrainbow Moonstone", despite the fact that it’s actually a variety of labradorite rather than orthoclase.  So a "Rainbow Moonstone" feldspar gem is closely related to Moonstone which is also a feldspar gem, but is of a different species of Feldspar.  Some Rainbow Moonstones look identical to a Moonstone and would need to be tested to tell the difference:
Rainbow Moonstone

However, per the GIA:   "To be called moonstone, a mineral’s actual identity is not as important as the beauty of its adularescence."

Many people enjoy wearing gemstones for their metaphysical properties, or the lore behind the gem.  I'm a believer of the power of the mind!  Here are some beliefs regarding the powers of these gemstones:

MOONSTONE: a stone of intuition and insight; helps balance emotions and relieves stress and increases patience; attracts good luck and good fortune; allows one to see into the future. Ancient cultures believed that if you hold a moonstone in your mouth during a full moon, you can see into the future.

RAINBOW MOONSTONE: a magical stone with powerful protective properties and deflects negativity; helps its wearer find their true path in life; a stone of intuition and insight; balances emotions and increases patience; increases creativity; clears the mind and senses to allow for calm sleep; helps bring out psychic abilities.

Moonstones and Rainbow Moonstones are closely related gemstones, but are not identical.  The information I trust the most and included here comes from the Gemological Institute of America.   Different information can be found on other websites, including, which has the world's largest database of mineral information and is updated daily.  On the Mindat website, there is information about exactly what IS a Moonstone, since the term "moonstone" is a generic term.  Even the discussions in the forums, with gem experts, find the classification of "moonstone" and "rainbow moonstone" to be confusing!

So, technically, a Rainbow Moonstone is really a transparent Labradorite feldspar mineral. Its chemistry is Sodium Calcium Aluminum Silicate.  Moonstone looks similar but is an Orthoclase/Albite feldspar mineral. Its chemistry is Potassium Sodium Aluminum Silicate.

They are both genuine gemstones that look very similar, and both are beautiful.  To ME, the Rainbow Moonstone with its more intense color display is far more beautiful, but that's just my opinion.