Ammolite, or opalized ammonite, is a rare gemstone made from fossilized ammonite shells and fascinates gem aficionados with its vivid colors. These bright colors are the result of complex structural and optical properties that affect how light reacts to the substance itself. Recent studies from Hiroaki Imai and co-workers explain how ammolite’s vivid colors are produced. In their follow-up work, they looked exclusively at specimens collected in Alberta, Canada.
Ammolite’s brilliant palette sparkles to life as light reflects off microscopic spaces between layers of aragonite plates. These gaps are only four nanometers wide, producing an incredible iridescent effect inside the gemstone. This complex yet beautiful structure enables an extraordinary play of colors, with ammolite displaying just about the whole color spectrum. The regular arrangement of layers of equal thickness in nacre further enhances its brightness. In response, ammolite has become very popular in the gemstone market.
To better understand these properties, the researchers used cutting-edge methods including electron microscopy and simulations. As these research scientists discovered, what makes ammolite special is that it’s completely different. In particular, they even contrast it with the thin nacre found in an ammonite fossil from Madagascar. This side-by-side comparison really shows how unique ammolite is both in terms of composition and color spectrum.
The research examined abelisaurid ammolite against the Madagascar specimen. It looked at what other shell types like abalone and nautilus shells do. This detailed study serves to further emphasize the unique characteristics of ammolite. Beyond this, it deepens our knowledge about the role of structural features in color production in natural substances.
“Ammolite shows (almost) the complete color spectrum.” – Gems & Gemology (2001). DOI: 10.5741/gems.37.1.4
Imai and his colleagues did rigorous research that opened the door to understanding this unique and beautiful gemstone. They recently published their findings in the journal Scientific Reports. Our research indicates continued study is needed to further understand the structural and optical characteristics of ammolite. Answering some of these questions will elucidate our understanding of other similar natural materials too.
