It's best to have proper lights, raytracing and photorealistic materials in the 3D model as your own results show.
In case they are not available but there's decent non-glossy shading in the rendered image you can separate the glossy metallic parts in the rendered image to new layers and apply to them the old "metallize with curves" trick. A non-glossy shading can be turned to chrome-like with partial tone scale inversion with curves. There cannot be color, so desaturate at first.
The result isn't especially impressive if the resolution is low like in your screenshot, but it hopefully shows the idea:
The USB connector is copied manually with the direct selection tool and pasted to a new layer. All color is removed with Image > Adjustments > Desaturate. A curves adjustment layer on the top has "next layer only"-switch ON.
Clipping with path would be a better way to make the selection and a there's no actual need for making a copy because masked adjustment layers would be enough.
Existing selection generates the right layer mask shape automatically as soon as the layer mask is created. The next "colorize it to gold" trick with Hue&Saturation layer uses a layer mask:
The color of the gold isn't the same as the real thing, but it can be good enough. The layer mask appeared with the next steps:
Apply Select > Reselect or Ctrl+Click the layer icon in the layers panel (I had a copy of the connector) to get an active selection
Insert the adjustment layer