Chai means life. It is a symbol of prosperity and inspiration for living. Hebrew letters have a number associated with it and the letters that spell chai: "chet" and "yud" equal 18. Therefore the number 18 is a common number used for gifts and celebrations, and generally good-feelin' (such as ModernTribe's phone number 324-1818: 18*18 = 324 and add two more 18s!). The necklace is sterling silver on an 18" sterling silver chain.