Why do you choose to integrate quartz and stone together? It is white and gray... they don't really go well together. The wall design looks great because it is far from flat, but you should probably switch out the quartz.
Actually, totally disagreed, white and grey go perfectly together. The dark toned down stone brick works amazing with the quartz, so I don't really understand where you're coming from. @Appul can help me out on this one.
I mean.. I get where he's coming from. Having too much white can look pretty off and make the colors look like they're competing against one another if that makes sense. You need to have more of 1 color than the other. I think it looks good, but overall I think it would look better with less quartz. Maybe keep the pillars white and replace the stairs with cobblestone or stonebrick. (:
Personally I see gray as black, so these colors are simply black and white to each other. When building, I tend to look for a darker/lighter color to contrast/complement the base but black and white don't really because they are straight opposites. That's just my reasoning (if it works for you keep it; it's not like the design is bad at all)