Curtains and tulle.
The scene contains a simplified model of a window.
The color of the curtains can be easily changed in the material settings.

https://3dsky.org/collection/shared/5255126  collection of my curtains.

For Corona render, it is recommended to install version not lower than 1.5, since the glossiness of materials is configured taking into account PBR.

If you are working in V-Ray version lower than 3.1, then be careful, in the materials in the BRDF section there is Microfaset GTR (GGX), if your version is older, then the BRDF field will be empty. Select Blinn, Phong or Ward - what is preferable for you.