The answer to this question is inspired by @DBM answering on a related issue:
How to write plain Greek in a text cell
I had a similiar problem, in summary:
- I use Style["Some text with greek letters", FontFamily->"Some
font, which includes greek letters"] and export it in pdf.
- As the result the greek letters are shown with Mathematica font, and the
rest with the chosen font.
- Hence Mathematica replaces greek letters automatically into Mathematica font.
Not always a desired behaviour.
Moreover, since version 10: 1) PDF export has improved significantly, but 2) Internal fonts and encodings are stored differently.
Find the file called FontMap.tr In linux I have it in "/usr/local/Wolfram/Mathematica/10.0/SystemFiles/FrontEnd/TextResources/FontMap.tr" , in Mac OS @DBM had it in "/Applications/Mathematica.app/FontMap.tr", and in Windows it is probably in the installation folder. Make a backup copy of it, e.g. FontMapBACKUP.tr
Open the file in a text editor. It contains the string CompressedData["Lots of weird characters"].
Open mathematica and define
FontMap=Uncompress["Lots of weird characters"] . I.e. copy-paste the string and run Uncompress on it.
FontMap[[1,2]] contains character codes of the symbols, which will be replaced into Mathematica font. You can see, what characters are they exactly by running
ReplacedCharacters = FromCharacterCode[#] & /@ FontMap[[1, 2]] . Furthermore, you can check, what do character codes signify by looking at http://reference.wolfram.com/language/tutorial/CharacterCodes.html .
For Mathematica not to replace the characters you like, you need to remove them from the list in FontMap. For example, I want Mathematica to replace only the characters which are not unicode characters. This means I should keep the characters with the code larger than 59391 (see the character codes web page):
FontMap[[1, 2]] = Cases[FontMap[[1, 2]], x_ /; 59391 < x] . Now greek letters and other unicode symbols do not get replaced.
Compress[FontMap] , this will produce "Lots of new weird characters". Replace "Lots of weird characters" by "Lots of new weird characters" in FontMap.tr file. Restart Mathematica.
Done, now the fonts should look as they should!
Disclaimer: The above, however, solves my problem but not yours. It seems like the font you were using does not contain greek letters as a part of it. To see, which available fonts contain greek letters at all, one can go to Format-> Font and choose writing system to be Greek. The listed fonts are the ones, which include greek symbols.