I used to buy Griffin silk thread which comes on a card already threaded up so is very easy to use. The length is only suitable for short to medium length knotted necklaces.
I did one of my own necklaces with the griffin silk and was dismayed when it snapped after a month.The silk thread just was not strong enough!
Since then I have used a professional synthetic bead thread using silk only for very light beads and seed pearls.
Very thick silk thread looks lovely for a single stone of silver pendant but in my opinion thinner silk needs to be used with caution!