"Who works in the V-Ray version is lower than 3.1, please be careful, the materials in the BRDF section are Microfaset GTR (GGX), if your version is older than 3.1, then the BRDF field will be empty. Choose Blinn, Phong or Ward - which is preferable for you. "If the version of CORONA is higher than 1.4:" For Corona render, it is recommended to install version 1.5 or higher, as the glossiness of materials is adjusted to PBR.