Smoked Glass Wall Light with Crystals & Chrome Back Plate

I can't quite see what colour is the glass cylinder. The first pictures gives the impression it's brown, but the on last picture it looks grey/chrome. But if it is grey, then how does it get to look brown/amber on the first pic?
When off the glass has a mirror like quality. Like a one-way mirror a reflective coating is applied in a very thin, sparse layer, so thin that it's called a half-silvered surface. When illuminated the intensity of light inside the glass is greater than the light outside so the mirror layer is not seen and the glass appears bronze.

Please could you tell me if these lights are IP-rated?
These lights would only provide a IP21 protection so can be used with caution in locations outside of bathroom zones 0,1&2.

Are these fittings dimmable with correct bulb?
Yes of course. This fixture was originally sold with a mains halogen lamp but was more recently supplied with a LED lamp. If you use a mains G9 lamp, or a dimmable G9 LED the fixture will dim on any equipment.

What colour do these lights look like when they are not on?
The glass shade will look almost mirror/chrome like when not lit (shown in third image) but when the light is on the glass will appear more smoked.