(A paper wallet is a paper wallet even if it is written on gold in tengwar runes that only appear when subjected to fire)
However, a ring inscribed with a private key controlling one bitcoin will lose its value immediately, because whoever comes into possession of (or ever sees) the ring will move the bitcoin.
"They started calling me four-finger Charlie“
http://www.businessinsider.com/charlie-shrem-arrested-bitcoi...
A B-grade fictional movie focused around "Ghost" who has the QR code to his wallet on his ring. Worth a watch if you're sick in bed.
Fun anecdote: the movie is depicted when $BTC is $250 and they're chasing after 30k and 40k bitcoin.
It's well known that people pay a major premium for things solely because they have words printed on them like "Calvin Klein", "Guess?" or "YSL". Jewelry branding is actually easier to make visually recognizable than clothes.
Though for a wedding ring you'd clearly need a different look.
Startup idea: Bitcoin wedding rings.
A beautiful gold ring with a private key engraved on the inside. Give your loved one the gift of BTC! Your commitment to each other, eternalized on the global blockchain.
Gentlemen may prefer blondes, but the modern woman prefers Bitcoin to carats of squeezed carbon. Status, store of value, it's all there.
(This is satire, but now I'm worried it will actually happen if the coinmania doesn't subside soon.)