public sealed class MosaicLayer : CompositeLayer, ArcGIS.Desktop.Core.IMetadataInfo, IInternalMosaicLayer, ILayerContainer, IMetadataSource, ITableDefinitionQueries, System.ComponentModel.INotifyPropertyChanged  

{
    //Path to mosaic dataset
    string urlItaly = @"C:\Images\countries.gdb\Italy";
    //Note: Run within a QueuedTask
    // Create a mosaic layer using a path to a mosaic dataset.
    // Note: You can create a mosaic layer from a url, project item, or data connection.
    mosaicLayer = LayerFactory.Instance.CreateLayer(new Uri(urlItaly), map) as MosaicLayer;
}

// Create a new colorizer definition using default constructor.
{
    StretchColorizerDefinition stretchColorizerDef = new StretchColorizerDefinition();
    var rasterLayerCreationParams = new RasterLayerCreationParams(new Uri("url"))
    {
        Name = "layerRasterName",
        ColorizerDefinition = stretchColorizerDef,
        MapMemberIndex = 0

    };
    // Create a mosaic layer using the colorizer definition created above.
    // Note: You can create a mosaic layer from a url, project item, or data connection.
    //Note: Run within a QueuedTask
    MosaicLayer newMosaicLayer = LayerFactory.Instance.CreateLayer<MosaicLayer>(rasterLayerCreationParams, map);
}