I need a geologist to explain this one. Moissanite has a Mohs hardness of 9.5. I guess it is easier to scratch than a diamond, but the scratability should be indistinguishable between the two for all practical purposes.
Not a geologist but Mohs hardness is an ordinal scale so the distance between 10 and 9 isn't well-defined. The numbers are defined as being specific minerals.
Diamond (10) is 4x as hard as corundum (9) which is 2x as hard as topaz (8).
(Moissanite is even better, so it should be preferred over diamonds unless I’m overlooking some other difference in their attributes?)
But plain glass gems look comparatively bland when used as jewelry.