Whoever has been watching my sketchblog knows my sketchbook is filled with swirls, as is the case with any paper that comes into my hands when I'm bored. Last week I was sketching some logos for a company at work, and that wasn't going very well - but I got an idea for something else, sketched it in a few minutes, ripped the piece of paper and put it in my bag. Later while driving in a bus I gave it some more thought and made the sketch on the right in my moleskine.
10 hours of hard work later, the pendant became real, and is so far my best jewelry work.
And I still have a bunch of sketches awaiting...
EDIT: Follow up post: Jewelry design - from sketch to reality II