because in season 2 it is explained..... charlotte is gracies granddaughted and she meets max ( the lewis on the past mermaids ) and he explains that he made the lockets that the girls wear. he made 3, one for miss chatem, gracie and julia. the girls find those necklaces.
yes!!!! she has got a different necklace from the others because she found it at the bottom of this little pool that she turned into a mermaid in. its a blue diamond that hooks up to the water wall now that is it the moon pool and rikki and cleo have one to the dimond necklaces can only work if they are together in the little circle like thing in behind the moon pool where they stand even though that they have the old ones they foget the others and collect the new ones from the mako island wall they get it by smashing a peice of rock and inside it has the dimonds so that is how they get it. here is a preview of what they look like... enjoy!
