Thanks @Rich33584, @benemer and all who looks at this thread!
This material is made with Blender and Cycles. It is quite simple. You need to create an effect like a mirror.
In Cycles you need the Glossy node with Sharp option enabled. This setup doesn’t take into account the Roughness paramenter. I have added a color ramp node, controlled by a facing layer weight node, to show a darker border outwards, which I see in some pictures, for example in Harley Davidson motorbikes:
That’s all.
Bye