The lighting is encased within a very unusual encasing. By the looks of it, it is custom made and crafted to have it's unusual shape. The unusual shape may be made by stained glass, or colored glass. Stained glass is usually created using fiber and silica. Because of the thickness, most of it absorbs the light (as we can see that not the whole shape is lightened up, as well as how the light does not show up inside the house), as well as reflect them (as parts of the color is not dark enough to absorb). While this shape is unusual, and is not very useful, it still does the job it is suppose to do, dim the light.
D Major would have an F# and C#, so it must be a minor -- d minor.
The relative major of d minor is F Major, so the key signature is b flat. There aren't any other accidentals, meaning it's not melodic or harmonic minor.
