I designed this for my mom as a present and since she gets a lot of questions about it, I decided to post it as well. The torus is approximately 37mm ...in diameter and 13mm tall. It was printed and polished by Shapeways in sterling silver for approximately $70 and weighs in at just 10g excluding the cord.
Voronoi tessellation takes a 3D matrix of randomly placed points and breaks it into various "cells." The area within each cell is closer to the cell's origin point than any other cell origin. The voronoi pattern for this necklace was created by distributing this pattern across a 3D volume and then constraining it with a bounding torus. The resultant curves were then made 3D with the T-Splines plugin. Unfortunately T-splines is a licensed plugin so I was only able to use it for free for a month before it stopped working. Hence, the attached Grasshopper file is missing the last couple steps. I've also attached the Rhino file for those who would like to experiment with different smoothing algorithms or make some tweaks to the design. If you need another file type, just let me know in the comments and I'll update the listing.