The shape of this pendant is derived from the Cahn-Hilliard equation, which is a differential equation that describes two mixed fluids separating into distinct phases. I created this pendant by running a numerical simulation of the Cahn-Hilliard equation in 2D, and then stacking frames from the simulation on top of each other and making a solid that represents one of the two fluids. Time moves forward as you sweep from bottom to top of the pendant -- at the bottom there are many small regions of the fluid, and as you move upwards they join up with each other in larger and larger segments, until they are all one.
The pendant has a 3mm hole for hanging on cord or chain to make a necklace. Here on Shapeways you can order the 3D-printed pendant by itself; you can get complete necklaces from my Etsy shop, although I do not keep the full range of materials that Shapeways can print stocked there. If you're interested in a necklace in a material or style you don't see there, just ask!