We have several shade guides to determine the appropriate shade of the tooth. The Vitapan classic is the previous standard of shade guide. It is still widely used but it has its limitation. For aesthetic zone, we decided to use the Vita3D master with the addition of bleached teeth shades. We were able to pick a shade that matches very well. The technology of all porcelain crowns nowadays is well-matured; but it is just as necessary to properly pick a matching shade for the tooth and the remaining tooth structure (stump shade) or else the lab technician would not be able to match the shade.
Removal of the existing crown was achieved carefully to ensure minimal reduction of the remaining tooth structure. Additionally, we chose a subgingival margin to hide the border of the crown and tooth. In other words, you cannot see where the crown ends.
The best indication of a well-made aesthetic provisional is that the provisional does not look much different than the final product, which was an eMax crown.