Hidden Door to Erebor Sterling Silver Charm Necklace Hobbit Inspired Tolkien Jewelry Thorin Bilbo The longest sterling silver charm measures 27x12mm (just over 1 inch long). Sterling key measures 22x8mm, and the sterling thrush charm is 13x12mm. Genuine .925 sterling silver components, chain, and clasp. Delicate rope-style chain with lobster clasp. From San Diego-based Asilomar Works.