Rare wire loop brooch or pin with stone

Here is a very old "wire loop" brooch or pin that predates the Civil War. It could have been a keepsake that belonged to a soldier's mother. It was dug on private property with the owner's permission between Chancellorville and Fredricksburg. It is in superb condition for its age, although the attachment pin is broken off. It measures 1 1/2 inches long.