Lexico defines "richness" as "the state of existing in or containing plentiful quantities of something desirable". However, its synonyms section includes no entries. Does anyone know any synonyms for "richness" concentrating on "quality" rather than "quantity"?
For quality, it's difficult because it depends on context.
Rich food can mean: with a lot of fat, with a lot of spice, and expensive. I would avoid using the word to describe food because it's frequently ambiguous.
Rich soil can mean full of nutrients, or full of humus (organic matter, not chick peas).
Rich colour would probably mean highly saturated.
The rich smell of cigars could mean that they smell expensive, that the smell is strong, or simply that the speaker/writer lickes it.