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

You should get her a heat-sensitive gold band

[Mordant]

that when put into the hearth, shows funny-looking script characters on the inside, resizes itself to fit the wearer's finger, and answers to the name of "Precious."

Re:Secret compartment?

[pcmills]

Do you eat it or give it to your mother in law?

Scribe tool

[qengho]

A diamond ring has the inherent functionality of being able to score glass. With a little practice, she can become adept at permanent warchalking on the windows of businesses with poor wi-fi security.