20:34 Jun 25, 2011 

Meanings of those letters in diplomas are lost in mistery :) At least, they are not widely known or used in any way.
Please check: http://www.armregistr.ru/index.php?option=com_content&view=a...
Бланк диплома бакалавра имеет серию и пятизначный номер -«Р № 00000». По завершении номеров серии «Р» буквенная серия меняется добавлением к серии порядковой буквы алфавита (например: РА, РБ и т.д.).
Бланк диплома бакалавра с отличием имеет серию и пятизначный номер - «ОР № 00000». По завершении номеров серии «ОР» буквенная серия меняется добавлением к серии порядковой буквы алфавита (например: ОРА, ОРБ и т.д.).

19:49 Jun 25, 2011 

Maybe, this "г" also means that the Diploma was issued by the "State-owned" ("государственный") rather than private body.

19:12 Jun 25, 2011 

Yes, that's exactly how it looks! Okay, do you mean a series of diplomas, such as a number of them all beginning with "г"? or a series, as in a series of types of diplomas? In order to send it it seems proper to me that I would have to have approval first, since it is a personal document

16:35 Jun 25, 2011 

Does the full title look similar to the following?
ДИПЛОМ
Г № 1234567

Then this is a series. But there are usually two letters denoting a series, not one, if I'm not mistaken. I'd like to look at the pic, of course...

16:07 Jun 25, 2011 

It is in the title of the diploma, located between "diplom"(you are correct) and the number of the diploma.

09:54 Jun 25, 2011 

Looks strange. Is it in the title of the diploma itself, or you met it somewhere in the text? The nominative for 'diploma' is 'диплом', not 'диплома'. So, a bit more detailed explanation would help me to help you :)