I think the diamonds in your chest are very... uniform. Funny, since uniformity is the main characteristic of a diamond, but for some reason I find these diamonds too uniform to be convincing. I can visualise them as maybe being a longer crystal (more like a rectangular prism with tapered ends), but when I think of diamonds I think of that classical "round/octagon top with a pointy bottom" shape; with dazzling light in all directions.
I think that's where I'm getting visual issues here -- I expect the light to be scattering off the diamonds, rather than a smooth graduation from light to shadow.
Perhaps try "randomising" the reflections more by scattering your four shades rather than having a smooth build-up from shade to highlight?
As for your ingot piles, I definitely prefer your first design -- the ingots turned on their sides in the second design feel out of place, and my experiences stacking items mean that seeing that kind of "jammed in" fit raises an immediate red flag... again, it's jarring because I expect something different.
In a heavily stylised aesthetic like Stonehearth's visual style, expectation is often more important than reality. Your diamonds are probably quite accurate for their scale, but I expect sparkly and the lack of sparkly-ness is what makes it feel weird. Likewise, when I imagine ingot piles I expect neatly ordered rows; like a scene from James Bond or some heist movie, where the camera pans around a vault filled with row upon row of identical ingots of gold bullion. Seeing those couple of ingots "out of place" in the second design makes me question why the other ingots were stacked in the first place, and that doesn't fit with the idea that these ingots were piled up for easy access.
But, with all of that criticism said, these are still great models and I'm impressed by your first forays into the area Hopefully you can refine your ideas and carry these themes forward, because there's a distinct lack of treasures to pile up in Stonehearth at the moment!