A string type that is used inside the BlockLayoutCell to set a predefined set of color shades for the cells. The colors are defined with sap.ui.layout.BlockLayoutCellColorSet. And this is for the shades only.
Shade A
Shade B
Shade C
Shade D
Shade E - available only for Fiori 3 theme
Shade F - available only for Fiori 3 theme