public CIMSymbolReference SymbolTemplate {get; set;}

{
  var aspectFaceRendererDef = new TinFaceClassBreaksAspectRendererDefinition();
  aspectFaceRendererDef.SymbolTemplate = polySymbol.MakeSymbolReference();
  // accept default color ramp

  // Note: Needs QueuedTask to run
  {
    if (surfaceLayer.CanCreateRenderer(aspectFaceRendererDef))
    {
      CIMTinRenderer renderer = surfaceLayer.CreateRenderer(aspectFaceRendererDef);
      if (surfaceLayer.CanSetRenderer(renderer, SurfaceRendererTarget.Surface))
        surfaceLayer.SetRenderer(renderer, SurfaceRendererTarget.Surface);
    }
  }
}