This is a purple heart. Purple is somewhat mysterious. Basically
💜means calm, noble, elegance, luxury, or mysterious love, and can also be used to express emotions between parents and children. However, in social media, purple heart emoji is more used in topics of U.S. military (The Purple Heart award) or BTS (a South Korean boy band). Related emoji:
❤💛💚💙🤎🖤🤍❣