Beautiful sterling silver and abilone shell BUTTERFLY shape - sterling silver, 925. HALLMARK on back is illegible but this piece is defintely sterling 925. I placed a tape measure in pics to show size.  Make is almost certainly Mexico and Taxco? I have seen a few others and this is how they were listed..

P.S. I have many many interesting jewelry items currently listed. Many makers, types, styles, materials, and from many different eras. Please take a look!!