Thank you for your kind comments. I downloaded your file and saw that each one was the same in the way the words were rendered, except one, and that was farsi-gtk.pdf file. The properties says that the font used was CairoFont produced by http://cairographics.org. After much searching and changing fonts I have not been able to find a suitable one, nor find the CairoFont.
Teus, are you able to pass on your CairoFont by way of attachment or tell me where I can get it. I shall carry on in my search for appropriate fonts.