Suggestions for Functional Jewelry?

szyzyg asks: "I'm getting married and my girlfriend and I have been looking around at rings and not really getting anywhere. I have all sorts of high concepts about what this should represent and I keep coming back to the thought 'nothing which is useless can be truly beautiful'. So I've been fighting with the idea of how to make a ring which has some use beyond simple symbolism... concepts like using magnetic minerals to turn it into a compass, or engraving some sort of measuring mechanism into it. So here's the challenge I'm putting to the Slashdot bright idea machine: How do I make a simple piece of jewelry useful? Someone out there must have better ideas."

Comments

If i made a "functional" ring,

[LittleBigLui]

it would be
One ring to rule them all,
One ring to find them,
One ring to bring them all
and in the darkness find them.

On the other hand, mood rings are pretty cool, too.

Re:When I got married...

[ArsonPerBuilding]

Gonna be redundant, as previous reply pointed out; do you have pictures of how the rings turned out? The design seems very facsinating and I would love to see the end result.