Only suggesting because you asked.
A like object ,in your case a class ring can be used to adjust your machines settings to try to discriminate all other objects. An example would be using the mate to a missing earring. Depends on pipe depth and what your detector does with iron also. Mine tends to stick on iron. That said gas pipes around my location are buried deep enough, guessing due to winter frosts,but then they should be below plow or rototiller depth as well? I could swing above them and adjust detector to ignore them and still find surface items. (I theorize). The hard part for me when trying to locate a specific lost item is not digging the others though when in doubt I might dig. Hope you try and then recover the ring. Good luck.