A safety clasp on the back of a pin is the one you are probably most familiar with as it is commonly used today. It is sometimes called a locking pin finding.
Hand made safety clasps appeared on non-Native American jewelry since the 1900s. The modern safety clasp began being manufactured in the 1930s.
But it wasn’t until about the mid 1940’s that safety clasps became readily available to Native American silversmiths and started to show up on pins and pin-pendants.
Prior to that time, the simple C clasp was used, which was a curled piece of silver on which to hook the pin – simple. If well made, it would be very secure; if not well made, the pin could bend or otherwise come unfastened.