Ok, here's my offer...
I have a small fake ruby on a little ring, that's intended to be inserted in a piercing in the body (the ring, that is, not the ruby). It's the colour that this thread seems to have taken, or at least pretty much so, and it can be attached more or less anywhere, well, within reason, anyway... Fineliner pens, flexible rulers n Sharpie pens are all very well, but surely you just can't beat a bright red ruby in the most unexpected of places... And unlike the Sharpie pen, there's no chance of it accidentally drawing blood, provided of course it's carefully inserted...
Do not go gentle into that good night.
Rage, rage against the dying of the light. (Dylan Thomas)