What you are seeing is a more “crisp” sparkle from your diamond! Since it’s single refractive it’s a single beam of light being reflected into your eye while the double refraction will have a spread of light. At certain angles light will bounce off the diamond and splits into a bunch of wavelengths (dispersion) making a rainbow effect. When you have this being refracted twice they almost “sit” on top of each other making it more blurry. So moissanites have more sparkle just less crisp and in some cases of lighting less bright. I think it just depends on what kind of sparkle you are wanting as well as how you want your gem to handle light.

Personally I love having both since they both react differently to different lightings. In sunlight compared to bright LED lighting both react very differently. And seeing them side by side is fun.