<Canvas xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
	xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">

   <Rectangle x:Name="test" RadiusX="4" RadiusY="4" Width="170" Height="200">
      <Rectangle.Fill>
        <RadialGradientBrush GradientOrigin="0.5,1.0">
          <GradientStop Color="#FFA051A1" Offset="0.5"/>
          <GradientStop Color="#33000000" Offset="1"/>
        </RadialGradientBrush>
      </Rectangle.Fill>
    </Rectangle>

</Canvas>

