I have a file with unicode symbols (russian text). When I fix some typo I use git diff --color-words=. to see the changes I\'ve done.
git diff --color-words=.
In case of unicode
For me best solution to this is setting export LESSCHARSET=utf-8.
export LESSCHARSET=utf-8
In this case both git log -p and git diff shows unicode without problems.
git log -p
git diff