Make, learn and talk about needle lace.
I'm new to the group, and "forum challenged", what weight thread would work best for jewelry? Right now I use oya to trim my dolls - for that I use my fine bobbin thread lace threads. Is silk the best thread for it? I appreciate any guidance.
I think it depends on what type/style jewelry you are interested in making, and where the piece is to be worn (how much wear it will experience will also influence how durable the thread needs to be).
I follow a blog and she has been experimenting with Oya and jewelry. I think she uses mostly heavy cotton thread (probably size 10 or 20), but she was experimenting with linen as well (3rd link below). I love the necklaces in the first two links--she uses Romanian Point Lace cord as the foundation for the Oya. A very good idea!
So I think almost any thread type/weight can be used, but think about where the stress/wear points will be for the jewelry you are designing, especially with finer threads. Because Oya usually has all the open single threads, that isn't very good for high stress areas, like attaching findings or clasps, so you might need to consider a way to reinforce them--like TotusMel's idea of using the Romanian cord for the highest stress part (around the neck and attached to the clasps) and hanging the Oya from it.
Good luck and be sure to share photos of your results!