You may have the most expensive or technologically-advanced watch available out there but the truth of the matter is, it will one day run out of batteries, break, or simply deteriorate. This next gadget, needless to say, never will; it will be able to tell time until, well, the end of time.
The sundial slash star dial ring-cum-pendant is made from pewter and can tell time without electricity, gears, or other needless technology. All it needs: the sun (and the stars for the star dial). Measures approximately 3.3 centimeters in diameter. Comes with a 30-inch black silk cord. Follow the link below for more details and a demonstration video.
To be able to tell time using the sundial, follow the link as well.