Vintage Jewelry Signed Coro Translucent Clear Round Lucite Real Mustard Seed Bow Faith Brooch Pin. This is a very awesome Coro brooch with a real Mustard seed inside. If you have faith the size of a Mustard seed this one is for you! There is a lovely Bow although it does show some signs of metal wear and light scratches due to normal use and age. Measures just under 1 1/2 inches in length. Shipped with USPS First Class Mail.