I believe it was zirconia, but I'll list the material as unknown. It sparkles beautifully depending on how the light hits it. ※It has been cleaned, but as this is a used item, please refrain from purchasing if you are concerned about scratches or the characteristic blackening of silver. It's one of my favorites, but I have too many rings now, so I'm selling it to declutter. I may change my mind and remove the listing, so if you're considering buying it, please do so soon... (＞_＜) ★☆★☆★☆★☆★☆★☆★☆★ silver925 Sterling Silver Sparkling Ring Black Zirconia Stone