What is double refraction in moissanite and does it matter?

The difference is massive. Cubic zirconia is 8 on Mohs, scratches in months, and looks flat. Moissanite is 9.25, basically as hard as diamond, and has real fire. A CZ ring is a 20 dollar disposable. A moissanite ring is a 500 dollar piece you can wear every day for years. Do not compare them.

Care is easy: warm water, mild dish soap, soft brush. Avoid chlorine pools, bleach, and acetone on the setting. Moissanite itself is tougher than most gems but the prongs and metal are the weak point. Check prongs once a year.

I disagree a little. Moissanite is beautiful but it has a very specific, almost rainbow flash that some people find unnatural. Try seeing one in person in daylight before you commit. In dim indoor lighting it can look grayish compared to a nice diamond.