I forgot to add the reason why there's a moral imperative to wearing a titanium ring instead of a diamond one: after saving yourself from drowning with the titanium ring, you can then descend to the ocean floor in an experimental diving suit, disarm a nuclear bomb dropped there by some nutcase that threatens a bunch of ocean-dwelling aliens, and impress them with your intended sacrifice (since your suit only has enough oxygen for a one-way trip) that they decide not to wipe out much of humanity with simultaneous tsunamis.