Inner circumference approximately 16.5cm. Approximately 6.5-6.9mm. Size adjustment possible, only to decrease. It has a deep red color similar to ruby, but there is no fluorescence, so you can see that it is not ruby. It's a beautiful, small-sized rubellite. ※ Although sourced from a reliable vendor, claims regarding coloring or treatment will only be addressed if proven as such by gemological identification. I am confident that the content is genuine, but as I have not obtained gemological identification, I kindly request that you refrain from purchasing if you do not trust the description.