This time I didn’t create a video tutorial. Instead, I made an online tool to calculate the most realistic specular value based on the IOR value. You can also download a .blend file that contains some math nodes to get the specular value automatically. In this article, I provide a table of IOR values of the most common materials and the equation used, just in case you want to understand how the tool works behind the scenes. I hope you find it useful. Good luck with learning the blender.