The base inner diameter is 16. Size adjustments are only possible for sizes 13-16. For sizes larger than 16, please confirm availability before purchasing m(_ _)m Top: High-clarity amethyst 14mm Lavender amethyst 10mm (rainbow sparkle) Amethyst 10mm * Amethyst is said to have effects such as stress relief, better sleep, improved concentration, warding off evil, fulfilling love, and promoting spiritual growth. It is also said to balance emotions and attract positive energy. * Lavender amethyst is said to have effects such as mental stability, healing, improved intuition, improved relationships, and improved judgment. In particular, it is expected to relieve stress and anxiety, and calm the mind. Videos are posted on Instagram ▶︎ ichigohime__ Please read the profile before purchasing. We do not accommodate metal allergies, but if we have the stone in stock, we may be able to remake the item without the metal parts, so please confirm before purchasing ( ´._.`) As this is completely handmade, please understand and purchase. * Please check the images carefully and make your own judgment. If you have any questions or concerns, please ask 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. (※) Price includes shipping, packaging, and handling fees. (※) If you would like a discount or a discount for multiple purchases, please leave a comment. Requests without a comment will be rejected. Please also read the profile (♡ᴗ͈ˬᴗ͈) We do not accept custom orders, only size adjustments.