plot DATA {using 1:2} with polygons
plot with polygons is currently treated as plot with filledcurves closed. Each polygon may be assigned a separate color by providing a third using specifier and the keywords lc variable (value is interpreted as a linetype) or lc rgb variable (value is interpreted as a 24-bit RGB color). Only the color value from the first vertex of the polygon is used. The border line type, if any, is taken from the fill style.
3D plots:
splot DATA {using x:y:z} with polygons {fillstyle <fillstyle spec>} {fillcolor <colorspec>}
[r][rt][width=3in,keepaspectratio]figure_polygons
set xyplane at 0 set view equal xyz unset border unset tics set pm3d depth set pm3d border lc "black" lw 1.5 splot 'icosahedron.dat' with polygons \ fs transparent solid 0.8 fc bgnd