I bought the plain rhinestone necklace from Forever21, but I think the ones on Ebay have better designs. I simply used the nail polishes that I already have. Plan the colors you want to use ahead of time because removing the nail paint from the necklace is really, really hard to get off.
Dannijo, along with Tom Binns has inspired me to make my own statement necklace. It took me a long time to finish this. Definitely not because of the preparation, but because picking the right colors that would mesh well together was harder than I thought.