If you've ever looked at 19th century patterns, you've seen a purse pattern calling for purse silk. I've often wondered what the purse silk was and have always substituted perle cotton crochet thread. I was cruising through the online catalogue for Fire Mountain Gems and Beads, one of my favorite places to be. If you're into beading or anything in that line, these are the people to know. I started thinking about the silk thread I'd seen before and wondering how it would work for purse silk. But I had no idea how the sizes worked.