Fun problem. This is a really nice stage, isn't it? I'd suggest squinting your eyes from across the room to "see" what color it is overall. As in brownish cream, dirty blonde, greenish gray, etc. Whatever you do, don't hold it 5 inches from your eyes and decide the colors you see that way will work. Since you want walls to complement it, choosing a background that will make it seem even more beautiful by being different, you could take the little-black-dress-for-diamonds approach. It's light, so a darker background would make it stand out beautifully and focus attention on it.

Just because you had a coffin lid before, doesn't mean it need remain so. Your goal and the surrounding areas are missing.If you're in progress...... you did a kitchen, or SHOW the kitchen... but nobody can advise based on your info thus far. Show the rest of the spaces beyond and flesh out the missing information....and the feel you want throughout.

Pick either a soft green or a soft blue/gray. Gray will not work. Either will work if you're selling. You don't need to do linen or cream on the walls to sell. Sometimes a neutral color will actually make the house sing more and a soft blue/gray or a soft green can do that. (In fact the house I sold in 2010 during the recession had shades of green on the walls and that's what the new owners loved. The condo I sold in 2016 had a green bedroom and that's the one room color she loved the most.) Your light fixtures are fine. In fact they're timeless. Don't change them

It isn't just the stone that is in the mix, your dominate color in the room is the floor/slider wood tones. I suggest a gray/green: You can see how nicely the walls work with the wood in this photo. IMO, it happens it is a winner, too. with the fireplace.