If you want to block a contact on chat from gmail, do the following steps :-
>> Sign in to your Gmail
>> Roll over your mouse pointer on the contact name on chat
>> A small box will pop up, now click on the downward arrow at the right bottom corner of that box and a small menu will come up and there you will get the option to block that contact just click on it.
eAnswers Team
If you want to block a contact on chat from gmail, do the following steps :-
>> Sign in to your Gmail
>> Roll over your mouse pointer on the contact name on chat
>> A small box will pop up, now click on the downward arrow at the right bottom corner of that box and a small menu will come up and there you will get the option to block that contact just click on it.