A wedding or eternity ring to some extent symbolises constancy and eternal loyalty, perhaps a good thing, maybe a euphemism for stagnation and not moving on. Eternity rings, however, are a bit of a scam to sell people yet another expensive piece of jewellery because engagement and wedding rings are apparently not already profitable enough. They also have the rather ironic property of being metallic. In other words, they are completely capable of conducting electricity, for which read a steady stream of electrons entering and leaving the ring. That's not exactly eternal. It means that a small fraction of the substance of the ring can be induced to leave it quite easily. Moreover, atoms are transferred between the ring and the surface of the skin, the ring and objects with which it comes into contact and so forth. Over a lifetime, and some rings are heirlooms, how much of a ring's substance is the same as when it was originally forged? Most of it perhaps, but not all of it.
Consequently, i suggest that genuine meaningful wedding and eternity rings be just that: the entire ring stays just as it was when it was forged, except perhaps for the neutrinos which happened to be passing through it at the moment your spouse slipped it onto your finger. I'll let those go. This means that rings should be made of non-metals. I have two substances in mind. One is sulphur, because it's a very good insulator and you would lose very few electrons. It is, however, fairly reactive and soft. The other is a ring made entirely of diamond. This is a slightly better conductor but it's really hard and won't lose much carbon. It's also diamond, though it would have to be artificial diamond.

So that's what i want. Wedding rings should be made of tiny black diamonds formed into a torus. Black to avoid the photons from entering or leaving, diamond because it's a non-metal and because it's really hard. Oh, and they should be made entirely of carbon twelve too, so there's no radioactive decay.

All that would also make them nicely expensive, and possibly more ethical than either natural diamonds or gold.
-- nineteenthly, Apr 18 2009

Solid Diamond Ring Solid_20Diamond_20Ring#1148430123
[xaviergisz, Apr 19 2009]

Have you ever tried to sell a diamond? http://www.theatlan.../doc/198202/diamond
lengthy, but good. [calum, Apr 19 2009]

You don't have to believe me when I say that the idea of a finger-ring made entirely of diamond occurred to me earlier this year. I wanted sparkling clear diamond though.
Then I figured they'd probably be really brittle, a pain to manufacture, and probably would look like glass if not faceted, or be painful to wear if they were - and forgot about it.

So - nice one.
-- Loris, Apr 18 2009


I think you could get away with larger facets. Done right, you might bounce light all the way around the ring.

It would be hard to cut after-the-fact. I wonder if it could be manufactured with the facets in place?
-- phoenix, Apr 19 2009


gee, i wonder why nobody has done this?
-- WcW, Apr 19 2009


Hmm. OK, i now have to consider how close [xavier]'s idea is to mine. I was thinking in terms of it being unchanging, hence the blackness, but he has the carbon twelve aspect. Was that for the same reason?
-- nineteenthly, Apr 19 2009


//Black to avoid the photons from entering or leaving// Diamond's still gonna radiate heat. I think what you want is a little black hole, tastefully mounted on a ring.
-- sninctown, Apr 19 2009


How about WIMPs?
-- nineteenthly, Apr 19 2009


Thanks for the interesting link, [calum]. I've long felt eternity rings were an unsuccessful scam. My mother had a diamond engagement ring and she was married forty-odd years ago. [Grayure]'s is a gold heirloom from my side, but English. Mine was Indian and gold but broke and i now have a titanium one because it's hard, cheap and not very reactive. If it becomes an heirloom, the metal may become virtually worthless in a couple of generations, which is why i chose it.
It surprises me diamonds had little intrinsic value, as hardness and high refractive index sound useful. I expect an artificial black diamond ring to be expensive because of the difficulty in manufacturing it, but i would expect it to be possible since they're used to coat blades, which i also expect not to be brittle.
-- nineteenthly, Apr 19 2009


//except perhaps for the neutrinos//

Thank goodness you included these. Otherwise I was totally gonna call you out on it. [+]
-- shapu, Apr 21 2009



random, halfbakery