In your description, the only thing that involves "authenticity" is the word "jade". As long as it is jade (no matter what kind of jade), it is real. There are many different types of jade; the color and shape of the jade reflect the craftsman's workmanship; the reputation of the maker also plays a big role. These three factors determine the difference in value. Therefore, it can only be: beginners identify whether it is jade and what kind of jade it is; and ask masters to judge the value.