I got the orbits from RioGrande, both in 14k. They have them in 18k too. Yes, the pearls are knotted on Beader's Secret in storm. Was deciding between Grey and Storm and went with the ever so slightly darker thread. Thank you for the wonderful inspiration!
And thank you everyone! ckrickett, you can easily make this tassel, I assure you!!
ETA: I love the orbit clasps for their ease of use and versatility. I can wear either side of the strand separately, or twisted together. I can also wrap one side around my wrist for a bracelet...or link together, minus the tassel and wear as a belt!