Version: 5.3 (switch to 5.4b)
The Fresnel Effect
Make your own

Material charts

Use these charts as reference for realistic settings:

Reference Chart for Metallic settings
Reference Chart for Metallic settings
Reference Chart for Specular settings
Reference Chart for Specular settings

There are also hints on how to make realistic materials in these charts. In essence it is about choosing a workflow (default or metallic) and obtaining relevant values for your maps or colour pickers. For instance, if we wanted to make shiny white plastic, we would want a white Albedo. Since it is not a metal we would want a dark Specular (or a very low Metallic value) and finally a very high Smoothness.

The Fresnel Effect
Make your own