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The grading of a diamond is extremely strict and precise and very different from grading moissanite. We have seen certificates for synthetic moissanite that are misleading and incorrect by diamond standards. Using diamond clarity grade terminology for any gemstone other than a diamond can be misleading. Just trying to compare colour to a diamond is also going to do harm to a synthetic moissanite.  

Grading terminology
We use the ICSL grading system for all gemstones except diamond, which uses percentages and plain English.   

Clarity terminology
Eye clean, very lightly included, lightly included, moderately included, heavily included 

Colour descriptions for synthetic moissanite
Colourless, near colourless, slightly tinted, tinted. As well as the obvious colours 
including: Blue, Green, Grey, Yellow, Champagne, Black and Cognac. 
On the Mohs scale of hardness synthetic moissanite is closer to 9.25 to 9.5 where diamond is a 10. Moissanite is the seconds hardest gemstone next to diamond.
Optical properties
You cannot compare the proportions of synthetic moissanite to that of a diamond. 
The optical properties are different, so cutting a synthetic moissanite to diamond proportions will block out light and not display its properties properly. The critical angle of a diamond is 25 and synthetic moissanite 22, so the angles must be cut differently to get the most out of it. Watch this quick video by Jeremy explaining how the critical angle works.

Source: Jeremy Rothon - The Gem Lab



What is Moissanite?
Moissanite is a beautiful lab grown gemstone . It occurs in nature but only in very small amounts with crystals that are too small to be used in jewellery. The composition of Moissanite -  Silicon Carbide - SiC .

How can it be a Diamond alternative?
The unique properties of Moissanite, it has 10% more Brilliance and 200% more fire than a diamond. 

Does moissanite weigh the same as diamonds?
No, it does not. Moissanite gemstone will weigh approximately 15% less than a diamond of the same size. Using a high precision jewellery scale will easily show the difference in weight. Always make sure you have the actual measurements of the stone you want, rather than the ct. weight.

Is Moissanite graded on the GIA diamond colour grading scale?
No, it is not, however at Namaqua Moissanite we do certify and grade our Moissanite through The Gem Lab in Cape Town. We provide a certificate that stipulates the Colour, Clarity, Finish and Dimensions, just like you would get with a Diamond. 

Is all Moissanite graded equally?
Not all Moissanite gemstone are graded accurately. You can ask your Moissanite supplier to provide you with a verifiable certificate, or take your stone to a gemologist to verify the information on your certificate is accurate.  You can visit The Gem Lab if you are unsure.

How hard is moissanite?
On the Mohs scale of mineral hardness moissanite is rated as 9.5 - hard enough to put in precious metals and totally suitable for everyday wear.

What is Brilliance, Fire and Scintillation?
Diamond & Moissanite fire is simply the coloured sparkle that you can see when the stone is exposed to light. In contrast to fire, brilliance is the colourless light that is emitted from the stone. Scintillation is a term that refers to the flashes of light you can see when you hold and move the stone.

Is Moissanite a Cubic Zirconia?
No, it is not. CZ is not an eternal gemstone and fades easily. Moissanite has extremely high scratch resistance and will never lose its brilliance or fire. 

How can Moissanite be distinguished from other colourless gemstones?
Moissanite can be identified by: 

  • Moissanite testers

  • A gravity test with a calibrated medium such as methylene iodide

  • Double refractive properties

  • Needle-like inclusions 

  • No gem can sparkle like Moissanite – it has more scintillation than any other gem


Is Moissanite available in different colours?
Yes! We have gone to the ends of the earth to source all colours Moissanite available. These colours include: Blue, Green, Grey, Yellow, Champagne, Black and Cognac. Our colour moissanite is not chemically coated and will not fade or scratch, unlike colour coated moissanite.

Got more questions?

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