It might depend on what metal is in the jewelry. Gold, Platinum, and Tungsten Carbide are very heavy metals and should be down deeper than the lighter metals, all things being equal. If you're finding can slaw, foil, and zinc cents, you might find a Titanium, Aluminum, or other junk type ring, but, not likely the heavy stuff. If you have an area with coins, I'd hunt it anyway, regardless, as there could be other interesting items in there too. Oddball pieces of jewelry and silver items can be anywhere.