Ok here is how it is done.

1. duplicate the layer.
2. step to the lower layer
3. use "filter>Blur>Gaussian Blur" on the lower layer
on my image of 2048 x 3072 pixesl and 180 dpi I started with
a radius of 7. The fun is that you can always put more Blur into it
if the result is to weak.


4. step to the upper layer and with a soft eraser tool erase the parts that need to be softend. Don't be shy.

5. now you can redo the lower layer for more or less result.
6. Have fun...!!!

Here are the results:
original
http://dehundt.nl/fotos/ruby-origineel.jpg

Top Layer:
http://dehundt.nl/fotos/ruby-doorkijk.jpg

Bottom layer
http://dehundt.nl/fotos/ruby-blur.jpg

result
http://dehundt.nl/fotos/ruby-result.jpg