Thank you for the great pictures, you can see the metallic effect very well here.
Can you also take a photo of Mozart's shimmering gold clothing, which has the same effect?
As far as I know there is no golden spot gloss. Spot gloss is simply a varnish that is selectively applied after the printing process. Unfortunately, this is also the problem if you have gold or silver elements, they can't have a metallic shimmer like a Steelbook or hot foil stamping. However, you can combine spot gloss with a silver foil. By printing the artwork on the silver foil, all colors appear to have a metallic shimmer, just like with a Steelbook. However, as with a Steelbook, not all colors should appear metallic (faces always look very strange due to the effect), opaque white is applied to the silver foil to selectively suppress the metallic effect.
Are the small dots or stars in the background flat or slightly debossed?