If you are just a guy with a picture on the wall and lava lights and a disco mirror ball hanging from your ceiling (like me), then its pretty much hopeless. But if you are gonna get picky and willing to redecorate, then try adding more light evenly around the subject. For display of metallic, you want at least some reflected light and you can control that by lighting it as a museum would. Controlled light is the key. Too much glare means that light is not controlled properly (from the common viewing area). If you can't move a light or control its brightness, tint, etc. then its not controlled and something needs to change, either the display place or the lighting. Rheostats and indirect light (bounced) are a good way to control light. If I don't want any reflected light then I don't use glass or metal. In the daylight you likely have windows and curtains to contend with so you can never open your curtains or blinds. In this case you have to choose between reflecting on the artist's perceived world (pun intended) or the real world outside your window.