Larimar center stones are 5mm. The smooth Turquoise stones and Sterling Silver spacer beads are 4mm. The necklace is 16″ with a 2″ extender chain. I was so excited when I finally visualized what to create with the Larimar beads I have had in my collection for years. I also created a Silver bracelet with the same Turquoise beads. Need earrings also? The Turquoise and Silver Earrings are a perfect color match.