The base inner diameter is 16. Only sizes 13-16 can be downsized. If you need a size larger than 16, please confirm if it's possible before purchasing m(_ _)m I post videos on Instagram ▶︎ ichigohime__ Please read the profile before purchasing. ※ Milky Rose Quartz is a stone that combines the love and healing effects of rose quartz with the maternal, stabilizing, and purifying effects of milky quartz. Specifically, it is said to be effective for emotional stability, improved relationships, promotion of self-awareness, and healing of the mind and body, and is especially recommended for women, those who want to have more peace of mind, and those seeking harmony in a new environment. I do not accommodate metal allergies, but if I have the stone in stock, I may be able to remake it without the metal parts, so please check before purchasing ( ´._.`) Please understand that these are completely handmade. ※ Please check the images carefully, make your own judgment, and ask any questions or concerns before purchasing. Returns, refunds, and exchanges are not accepted after arrival. I am a handmade seller! Please understand. If you are looking for perfection, please purchase from a shop. (※) The price includes shipping, packaging, and handling fees. I do not understand requests for bulk discounts based on the shipping cost, so I will decline them. (※) If you would like a discount or a discount for multiple purchases, please leave a comment m(_ _)m If there is no comment, I will decline. Please also read the profile (♡ᴗ͈ˬᴗ͈) I do not accept custom orders, only size adjustments.