Visualizing Spatial Relationships - Data Points: Visualization That Means Something - page 287

A diverging color scheme, as shown in Figure 8-13, might be good if your
data has a two-sided quality to it, such as good and bad or above and
below a threshold.
FIGurE 8-12 Sequential color schemes with ColorBrewer
FIGurE 8-13 Diverging color schemes with ColorBrewer