Wow. These are beautiful. To quote the original eBay listing:
A gorgeous pair of vintage Victorian/Edwardian heel clips! They were made by the Fishel Nessler Co, and are marked on the bottom FN&Co. Fishel and Nessler was located on 5th Avenue in New York, and made their lovely pieces between 1885 and 1937. These early clips are made with ornate and detailed metal filigree set with rhinestones. They are designed to fit over a French heeled shoe.