This question has been asked to me multiple times, so I decided it’s time for a post!
A single pigment color made from copper, Rich Green Gold is a glowing, earthy greenish-yellow. Unmixed, it may read as green, but in mixes it functions more like a muted yellow.
One thing you’ll always read about Quinacridone Gold is that it used to be a single pigment, PO49, until 2017, when the supply of that pigment ran out altogether. Artists bemoan the loss of this pigment which, in retrospect, they imbue with almost magical properties. I’m too young in watercolor years to have tried it, but personally, I love the mixed Quin Gold hues that you can find now, so I’m happy!