I think Harry transformed her body into the gold ring. Then if Dumbledore were to search Harry for transmuted things (as he did), he would find the stone. Harry carefully set the ring and gem far apart, so when Dumbledore undid the transmutation on the stone it did not affect the ring. The brown color was to make the stone more attention seeking. The rest of Harry was carefully checked for magical things, but the ring itself was never checked for magic other than in combination with the stone.
Standard stage magician trick - make people look at something else.
Harry has shown a remarkable aversion to actually lying in past, so doing so here seems unlikely, and I don't see any loopholes in those answers. An interesting theory, but if it's true it implies some things about Harry's character growth.
I think Harry transformed her body into the gold ring. Then if Dumbledore were to search Harry for transmuted things (as he did), he would find the stone. Harry carefully set the ring and gem far apart, so when Dumbledore undid the transmutation on the stone it did not affect the ring. The brown color was to make the stone more attention seeking. The rest of Harry was carefully checked for magical things, but the ring itself was never checked for magic other than in combination with the stone.
Standard stage magician trick - make people look at something else.