Jewels of the Sea

A rather infamous series of islands known for being both incredible valuable but also cursed.
No one knows if the curse is real or not, but legends say that if you steal any valuables from these islands you are fated to die shortly afterwards, and either by coincidence or an actual curse it seems like this is most certainly true.
This has become especially common after these islands were unintentionally transmuted by a surge of wild magic from a sorcerer named Vessa Elsen who turned the islands, going from bottom left to top right, into Sapphire, Amethyst, Diamond, and then Emerald.
For decades, pirates and bandits have been pillaging around here, desperate to try and take whatever they can and prove the curse wrong but seeming caught in an endless war around these isles which seem to have no real living residents, at least not by anyone's known estimations.