There are two textures here. One for the marble and the other for the glass. The marble texture is really easy to make. It has a shinny surface that reflects the window. I like the way the glass has the suggestion of a background reflection. It’s a trick really, the texture is made that way.
If you want to join the online session, see this blog post:
What kind of textures would you like to see covered?
marble, glass, brickwork, blockwork, weatherboard… what else?