edit: seems that moissanite (silicon carbide, perhaps unsurprisingly) is another diamond-like (though hexagonal crystals vs. cubic for diamond or CZ) gemstone that is actually harder than sapphire and less prone to fracture than diamond.
If we're talking about 'quality', CZ just doesn't compare for longevity. That said, unless you're talking about a daily-wearing-for-many-years piece of jewelry (i.e., an engagement ring), CZ is just fine for most folks, especially considering the cost difference.
> The adults around me couldn't explain scientifically what the actual difference was between a CZ and natural diamond.
I was told growing up you can just check with window glass. If the gem scratches it's CZ and if the glass scratches it's diamond.
CZ is very cheap costume jewelry and won't last as it scratches and dulls so easily
one of the victims said she had doubted the ring he gave her was real, but he just scratched a mirror with it to prove it was real. Then she said "it was only later after he left that I found cz can also scratch glass"
They were simply dismissed as more trash belonging in the gold-plated case. It's hard to appreciate how much less informed people were back then - we're talking pre-internet. The adults around me couldn't explain scientifically what the actual difference was between a CZ and natural diamond. Just one was a fake, held little value, and was a sure way to lose your fiance.