Graphics3D[{
SurfaceColor[RGBColor[0,.7,.8]],
Polygon[{{1,-1,1},{1,0,1},{0,0,1}}],
SurfaceColor[RGBColor[0,.7,.8]],
Polygon[{{-1,-1,1},{-1,0,1},{0,0,1}}],
SurfaceColor[RGBColor[0,.7,.8]],
Polygon[{{1,1,1},{1,0,1},{0,0,1}}],
SurfaceColor[RGBColor[0,.7,.8]],
Polygon[{{-1,1,1},{-1,0,1},{0,0,1}}],
SurfaceColor[RGBColor[0,.7,.8]],
Polygon[{{-1,1,-1},{0,1,-1},{0,0,-1}}],
SurfaceColor[RGBColor[0,.7,.8]],
Polygon[{{1,1,-1},{0,1,-1},{0,0,-1}}],
SurfaceColor[RGBColor[0,.7,.8]],
Polygon[{{-1,-1,-1},{0,-1,-1},{0,0,-1}}],
SurfaceColor[RGBColor[0,.7,.8]],
Polygon[{{1,-1,-1},{0,-1,-1},{0,0,-1}}],
},
  AmbientLight -> GrayLevel[0.7],
  PlotRange -> {{-1,1},{-1,1},{-1,1}}
  ]
  