CedGooglePlusComments

Google+ Comments shows by default the best comments and there's an option to show the most recent comments. You can also restrict the comments to the people from your Google+ circles.
Google+ Comments is not available for private blogs and for blogs with adult content.

★ Add Google+ comments to selected or all Joomla categories,
★ Choose among 7 Icons in frontpage to let user add comments,
★ Display comments counter,
★ Comments moderation support. (If you provide a Google+ Profile ID)
★ Comment box width can be set.
★ Also display social interactions made on Google Plus.
★ HTML5 implementation
★ Works on Mobiles and desktop