Miraculous mermaid

Marinette is a mermaid, she's a princess mermaid.
On her 16 birthday she is given a necklace which contains power, power to keep her underwater kingdom safe, a power that is so powerful that it can do great things, heal, create, fix and luck.

This necklace was passed on in many generations but it wasn't always like that, once this necklace was used for evil but ever since it got separated from its twin, the unlucky part.

It gained its own power which was lucky, it was and still is used for good however the other part was lost in the dark part of the sea, which no one dares to cross.

Myths say that if the necklaces ever reunite, great powerful power would be released, but if the necklaces fall In the wrong hands hell would break lose.