"Serotonin Necklace, Chemistry Necklace for Women. Serotonin is the chemical that produces happiness. This necklace is a great message that you literally create your own happiness and nobody else does. ✅ PRODUCT DETAILS * Material: solid sterling silver. * Pendant is 1.3mm thick. * The total length is the chain length only, it does not include the length of the charm. * All necklaces come with a 2\" extender for adjustable length. ✅ PRODUCTION & SHIPPING INFO 📌 Important: please be aware th