为什么我不能在c#中把隐式运算符从基类写到派生类呢?

public class Derived : BaseClass
{
    public Derived(string name) : base(name) {}

    public static implicit operator BaseClass(Derived derived)
    {
        return new BaseClass(derived.ColorHex);
    }

    public static implicit operator Derived(BaseClass baseclass)
    {
        return new Derived(baseclass.name);
    }
}
public class Derived : BaseClass
{
    public D