Hi Barbara, could this be knitting yarn? Have a look at this site, it has some explanation: http://www.miniknittingstuff.com/yarncount.htm. "Cord" might refer to the type of twist.
The other option could be silk tapestry thread. This is known to have a very tight twist and is usually only used on canvas. Like Linda suggested, it might be also suitable for surface embroidery, like couching.
I also found references to Mulberry cord (silk) which is also used by jewellers for necklaces and woven bangles because of its strength. Seems to be quite strong and not too thick.
I've never heard of silk cord yarn before. It might be known under different name.
Thank you both for your help on this :)
I'm in the same carriage of that thought train, Sharon :) Plus silk has me spellbound at the moment
I'm a bit rusty on yarn counts, but remembered that "nm" is an abbreviation for a weight of thread, so Googled it. Madeira have provided a page on understanding thread counts:
Personally, though, I'd play with it and see what I could do. Even thread too heavy to be stitched with can be couched!
What a disappointment! I thought, judging by th photo , the silk would be a lot thicker, but it is very fine the equivalent of one and a half strands of embroidery floss!
I am dyeing some and will use in multiple strands or maybe wind onto a bobbin and use in the machine?
I've never been good with a machine, so I can't advise on that!
You can certainly use multiple strands in a hand-needle, and maybe some of the Japanese embroidery people could tell you how they twist strands themselves?
Thanks for all the helpful advice, I'm sure it won't go to waste!