There are so many different materials used in jewellery during the 1930's-50's. I like to find out about the inventive ones, like an article in a 1940's magazine with instructions on how to make a brooch from a fir cone, by removing the tip of the cone, attaching a leather leaf and cord and painting the fir cone with enamel paint. Leather seems to have been used a lot and I guess much of it would have been off cuts from old clothing and household materials. Below is an example of a leather corsage, which shows signs that it would have had more paint on the surfaces.
Another example, again from the 1940's is this "Stockings" brooch. Made from stocking material that looks as though it has been dyed different colours. I can imagine someone like Ginger Rodgers wearing this one!