The base inner diameter is 16. Only size adjustments down to 13-16 are possible. For sizes 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. ※ The effects of blue chalcedony are said to improve relationships and bring stability and healing. It is believed to give good energy to groups and enhance feelings of compassion and empathy. It will soften a tense atmosphere and create a calm mood. It is also recommended when you want to deepen bonds and connections. ※ The effects of aquamarine are known for stress relief, mental stability, building good relationships, and as a charm for "happy marriage." It is considered a versatile stone that calms the mind, enhances communication skills, and is also used for safe travel prayers, especially recommended for those entering a new environment or wanting to smooth out relationships. 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 ( ´._.`) As it is completely handmade, please understand and purchase. ※ 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 handmade! Please understand. If you are looking for perfection, please purchase from a shop. (※) The price includes shipping, packaging, and handling fees. I reject bulk purchases with a discount on the shipping fee because it doesn't make sense. (※) If you want a discount or a discount for bulk purchases, please leave a comment m(_ _)m If there is no comment, it will be rejected. Please also read the profile (♡ᴗ͈ˬᴗ͈) I do not accept custom orders, only size adjustments.