Belle controlled

You are an inventor and have to work with your biggest competitor on your current project. Niklas Carmel is arrogant, conceited, mean, but unfortunately also clever and attractive. You have discovered an emerald that, when combined with the right metals, can influence people's minds and make them do whatever you want. Mind control! You have made a breakthrough today. You have incorporated the emerald into a necklace and whoever wears it, must obey the thoughts of the person holding the second half of the emerald. You write down scientific notes while Niklas puts the necklace away safely. 2 hours later, you have finished everything and drive home to your wife Belle. You want to go out tonight, but when you arrive, something is wrong. She attacks you with a knife in the hallway, the green emerald necklace glistening around her neck.