The differences between Moissanite and Diamond are plenty!
Keep in mind, when we're talking about Moissanite, we're actually talking about the Created Man-Made Moissanite that you see on the market today. Not the genuine stone found in nature!
The Moissanite in today's Jewelry is created by a company named Cree Research. In the late 1990's they came up with the formula to almost perfect the stone found in nature. Tiffany & Co. actually came up with the name!
But, while it may resemble a Diamond in many ways, the Chemical Composition and Optical Properties are totally different.
Moissanites weight less than Diamonds do!
They also give off more Brilliance and Fire (Sparkles) than a Diamond. 10% more Brilliance (White Light), and 150% more Fire. (Colored Light) That's a lot of light!
So just looking at a Moissanite stone, you'll see it sparkling like crazy. Not necessarily a bad thing, but it is a big sign that it's not a real Diamond. (Think of a Disco-Ball's flashing lights!) (CZ's also have more Brilliance and sparkle than a Diamond! Read: CZ VS Diamond)
Few Inclusions
Moissanites can be created with very few inclusions also. That's awesome! They look clean, almost flawless. (Most man-made Gemstones are) Moissanite, if graded the same way that a Diamond is, would be in the VS Clarity range. To the naked eye, it would be clean, and even under a microscope or 10x Jewelers Loupe you'd only see a couple of small imperfections or inclusions. Not too bad!
Moissanite Color
But let's talk about Color!
This is where Moissanite fall short! The natural color of Moissanite is Green, Yellow or Grey! (Lovely) White is NOT an option! (As of yet!) No pure White Moissanites have been created or perfected. The closest the laboratories can get to White is a Near Colorless Color Range like I-J-K. To me, you can always see a stark Yellow Cast to them.
They just appear dark and dirty.
So while the Clarity may be there, the Color isn't! Light Yellow Stones just don't look appealing, and they certainly don't sell well. Diamonds rule in this aspect!
So all in all, man-made created Moissanites have come a long way since their initial discovery about a Century ago. They are durable, heat resistant, and resemble a Genuine Diamond in many regards. They even sparkle more than a Diamond, Cost way less, and are very clean of any imperfections...
But should you buy Moissanite stones versus Diamonds? Read on...