Fibonacci's Golden Spiral Steampunk Pendant Necklace by Alchemy Gothic. A flat antiqued pewter Renaissance-style scientific instrument pendant in the form of a Nautilus shell, with overlaid etched brass detail. For 5,000 years the Golden Mean has been a central tenet of technology, and decoded by Fibonacci in the Middle Ages. The famous Fibonacci sequence is engraved upon the reverse. The Fibonacci Golden Spiral pendant necklace comes on a 21" chain. Width 1.26" x Height 1.97". Made of lead-free fine English pewter exclusively by Alchemy Gothic.