

I don’t think the Mona Lisa is a good comparison. When it comes to old paintings, there’s a lot of interesting stuff happening underneath the surface image that tell an interesting story. They can be analyzed to see all the mistakes that were corrected, or changes that were made to the painting. I believe it was also commonplace to reuse old canvases, so with the appropriate technology, you would in theory be able to look underneath and see everything that came before as well. So I can definitely see why that would be valuable.
Still don’t understand diamonds though.
As I understand from the other comments, it’s a place to put the dishes after they’ve been cleaned and ready for rinsing? The way I’ve always done it is I clean the largest vessel first, then everything goes into that vessel until it fills up, then do a round of rinsing. If I don’t have a large dirty vessel, I take out a large clean mixing bowl for this purpose.