Curtain. Two panels with a pleat in the shape of a glass. Panels with lower edges. One panel is gathered with a tieback, the other is straight.
The scene includes a simplified model of windows in the wall and a simplified model of cornices.
The set is grouped for convenience. In the export file, all objects are ungrouped.
The colors of the model can be changed in the material settings.

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

For Corona render, it is recommended to use version no lower than 1.5, as the glossiness of the materials is set with PBR in mind.

If you are working in V-Ray version lower than 3.1, please note that the materials in the BRDF section have Microfaset GTR (GGX) set; if your version is older, the BRDF field will be empty. Choose Blinn, Phong, or Ward – whichever is preferable for you.