Cycles render for Facebook without color I am writing to you because I have a problem with files to use for 3D posts on Facebook.

I had done a lot of tests all using BLENDER RENDER: file had the color and the characteristics that I had set by the nodes, everything was ok but did not have the shine of the Glossy BSDF.

Then I changed the rendering engine in CYCLES RENDER, and checking from the rendered mode it has the shine I needed, I again exported my work in .glb for posts on Facebook, but so I see it all as gray as in the picture .

A) Can you explain to me why and how to solve?
B) Can someone tell me how to set a colored background?

Link to post (.glb) with Blender Render: 
https://www.facebook.com/paginaprovaSynptc2018/posts/2189922261052625

Link to post (.glb) with Cycles Render:
https://www.facebook.com/paginaprovaSynptc2018/posts/2191151167596401

Thank you all
You have to consider that materials in cycles get translated. As the  glTF 2.0 Exporter documentation says: 


  Blender supports two material settings: One for Blender Render and one for Cycles Render. Fortunately, the glTF 2.0 Materials can be simulated using the Cycles Render by implementing a custom node tree


You can't just write materials in cycles and then translate them, this will just not work. You have to use the ones provided by the repo. 

This is really well explained in the documentation (I'm assuming you're using this exporter):

https://github.com/KhronosGroup/glTF-Blender-Exporter/blob/master/docs/user.md