While rummaging through my stash, I found a sparkly gold embroidery thread (DMC brand, on a spool, polyester/rayon blend) and wondered how it would combine with some Lizbeth size 10 cotton. I'm reporting that there were many tension problems! I'm not sure if it was because the 2 threads were different sizes, or because they were different fibers.
But, I doggedly persevered, and managed to finish the heart (which is from my "Unfolding Heart" pattern). I also added beads (which are not in the original pattern) and finished it off with gold filigree connectors and gold plated chain. I think it looks pretty, but this heathered version will likely be a one-of-a-kind, since it was so labor intensive to make with this particular combination of threads.