Inner circumference approximately 16cm Around 10mm Size adjustment negotiable This is high-grade blue amber from Mexico. It exhibits a stronger fluorescent reaction than regular amber. Blue amber is the name given to amber that appears bluish even in natural light. ※ We purchase from reliable vendors, but claims regarding coloring or treatment will only be addressed if proven as such by appraisal. We are confident that the content is genuine, but as we have not obtained an appraisal, we kindly request that you refrain from purchasing if you do not trust the information.