Since the Polo is silver and he doesn't like gun metal alloys, the next best option would be black. I've seen some lovely Polos with matt black alloys and they are to die for.
Even the service guys here said that alloys can void suspension warranty but then they backed out when I said that they themselves sell aftermarket alloys for a higher price compared to tyre shops outside. They then said that I can go ahead and fit alloys. These guys, I tell you.
BTW, just realised. He has the new HL model right? Those come with beautiful alloys as stock. And Momo has very similar alloys but in a grey/matt black color. That looks wonderful. If there are good painters where you're at, you could try painting your alloys a matt black color. Should look really beautiful