Hi Ada,
Moissanite from Charles and Colvard definitely is prone to chipping at the girdle but not at all for the reasons Gold and Gems is saying. Moissanite was and is cut with very thin girdles (thinner girdles = less rough used = cheaper to make) and thin girdles are inherently chip prone. Moissanite never has a faceted girdle, so faceting has nothing to do with "making it more prone to chip", otherwise Moissanite would not have had so many chipping problems.
Any very thin girdle is prone to chipping - moissanite, diamond, etc. You have a very thin area with a lot pressure potentially hitting it from the prongs or during wear. It should be no surprise that a thin fine line (very thin girdle) is less tough than a thicker one (thin-medium girdle).
To claim that polished is more chip resistant than faceting is just sly marketing to explain why their cutters don't do the more time consuming step of faceting the girdle.
If faceting increased chip risk I assure you the most valuable diamonds such as H&A round diamonds, would not all come with faceted girdles.
But all H&A diamonds do have faceted girdles and no issues with chip risk.
Customers can decide if they want their diamond alternative to be the same as H&A diamonds (fully faceted, Amora) or the same as CZ (polished, Moissanite, etc.) but to try and claim they are not faceting to make it more chip resistant is pure spin on producing a stone more cheaply. Contact any H&A diamond vendor and ask if they think polishing their girdles would be an improvement over faceting
Hope that helps,
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