No text, but a visual code

[Koen G]

That is an amazing parallel, Antonio. I placed them together so people can see it better:

   

After this comparison, I think we can be almost certain that the central Rosettes items are rich vessels of metal, probably gold. Also note that the only coloring on them is yellow, which we must assume has faded over time and was once much more bright.

This detail is part of a now dispersed altarpiece made ca. 1435 in Basel, where Konrad Witz worked most of his life. (He grew up in Rottweil, not too far northeast of Basel). It is called a "Salvation Mirror" altarpiece because it is based on scenes from the popular Speculum Humanae Salvationis. 

I don't think we can draw any conclusions about the contents, only about the fact that these vessels are meant to be splendorous. Compare this scene from the same altarpiece, where Abisai brings water to King David: You are not allowed to view links. Register or Login to view.