Vintage Handmade Mother of Pearl US Navy Clip On Earrings Jewelry

They appear to be handmade & from the 40’s. I don’t have much info on them but the note in the last pic is how I received them. Im assuming its Mother of Pearl. If it’s not- please feel free to correct me. The clips on the back look like they would be easily removed if you wanted to change them to posts. Antiqued silver (possibly sterling but I have no idea & could not find any marking) center that says USN with an anchor. They measure approx 1.25”.