In movies, you might see diamond rings being cut in half for dramatic effect. However, in reality, cutting a diamond ring in half is not a simple or common practice. Diamonds are extremely hard and durable, which is why they're often used in cutting tools. To cut a diamond in half or reshape it significantly, you would typically require specialized diamond cutting equipment and expertise.
Additionally, it's important to note that cutting a diamond significantly reduces its value, as it involves altering its natural state and shape. Therefore, such actions are not recommended for valuable diamond jewelry. If you have concerns about a diamond ring or need it resized, it's best to consult with a professional jeweler who can provide appropriate advice and services.