Most likely a company officer’s lady’s sweetheart pin; jeweler made.
The 13th Cavalry was organized in 1901, and this appears to be the period of this finely made lady’s pin for wear on a scarf, or elsewhere. Jeweler made with great detail, and about 2 3/4 inches.
With the way the pin is attached to the bottom of the insignia, I doubt how secure it would be placed on a uniform collar, and that is why I feel it is a sweetheart piece. The number ’13’ is silver plated, showing the gold on the reverse. Gold wire is wrapped around the grip of each saber. The mounting rings on the scabbard are holed, not solid. The two branch hilts are pushed in some, and one side the outer branch is broken off.
A very nice piece of work.