For your consideration is this large safety pin. I read they were used often used to hold keys for laundry or as horse blanket pins. Unlike most that are plain, it has a nice Indian Navajo applied design with a genuine turquoise stone. I believe the S is that artisan that did the work. I have seen some curved like this and some straight. It is a think sturdy piece. It is marked Risdon Key Tag. I think it is silver plated with some loss. Fully functioning but you need a strong hand. It could benefit from a cleaning. I will clean if requested. Stone is secure.
It measures just shy of 5 inches by 1 and 1/8.