What was called a masterpiece in the Middle Ages?

In the Middle Ages, the concept of “masterpiece” was understood as the best product, an example of a product made by a craftsman using his equipment. Such a product could have been made by an apprentice. Only after the presentation of the masterpiece to the public, the artisan could enter the workshop and open his own workshop. The “face” of any workshop was a masterpiece until 1900. But even now, the owners of small workshops and large enterprises are trying to present to the public a product that would pleasantly surprise a potential customer or buyer.