Antiqued Round Seal - Initial - O - Green Shamrock Necklace and Clover Earrings Jewelry Set. Charm size is approx. 0.75 x 0.63 x 0.11 inches (HxWxD) not including loop. Silver tone faceted ball chain necklace is 18 inches long with a spring ring clasp. Green Crystal Post Earrings have a steel post and a plastic comfort ear nut. Sweet green Irish Shamrock is hand painted enamel and is a famous symbol of Ireland and St. Patrick s Day. The symbol was used be St. Patrick to spread Christianity as a symbol of the Holy Trinity.