I just finished this and shipped it off to one of my galleries. The botanical portion is made from BronzClay (Metal Adventures brand), and then riveted to sawn nickel silver and copper which has been textured.
The botanical image was made by carving into a soft block material. This is yet another way to use one’s own images to make jewelry.
One of my followers (wow, doesn’t that sound awesome?!) suggested I do a post on two-part silicone mold making. I will write that as soon as I can, as well as posting about the carving method used above.