Super Ideal Cut Moissanites: Part 2 Refractive Index

Super Ideal Cut Moissanites: Part 2 Refractive Index

While moissanite is a very diamond looking material there are certain gemological features about them that distinctly separate it from diamond.  Two of those distinct features that separate it from diamond are ... 

  • The fact that it is doubly refractive as opposed to singly refractive and
  • Moissanites have a higher refractive index than diamond does. 

To say a gem is doubly refractive simply means that when one beam of light enters the crown, two beams of light will exit.  Singly refractive means when one beam of light enters, one beam of light exits.

As a gems refractive properties are inherent in the gems crystal structure there is nothing that can be done to make a doubly refractive gem singly refractive.  This is what accounts for the higher dispersion we see in moissanite when we observe them in spot lighting environments.

The other aspect is the gems refractive index.  The refractive index is the measurement of the speed of light as it travels within a gem before it exits.  Diamond's refractive index, one of the highest is 2.42nm.  Moissanite is a whopping 2.67nm!

So ... is this a good thing or a bad thing?  Neither really but what's important to know and understand is that the refractive index of a gem, in this case moissanite, can make it appear more like diamond OR NOT depending on how you cut the gem when you are targeting a specific set of optics.  Let's take 2 gems, both cut to the same identical specs but one has a refractive index of 2.42nm (diamond) and the other with 2.67nm.  Look how different their ASET results are.

The bottom line is this.  If you are buying a moissanite and you want it to appear MOST like diamond you obviously want to get the gem whose ASET, which translates to light performance, is most like diamond. When you purchase an August Vintage Moissanite you are getting precisely this as we are perhaps one of the only companies on the planet that knows how to properly alter the gems overall proportions to mimic the optics and light return of their diamond counterparts be it Hearts & Arrows, August Vintage Cushion, European Cut or any shape it is that we are going to feature.  AV Moissanite does just this.

This is an actual ASET of an AV Moissanite Hearts & Arrows next to what we most commonly see on the market worldwide. Besides adapting the proportions and refractive index of our moissanites to mimic diamond optics there is also a world of difference in the precision of the cutting.  We will cover these aspects in our next article.

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  • Jonathan Weingarten
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