Note: If you do not need install apk you can try an online emoji keyboard: http://goo.gl/ML1j5J

It is an Emoji font you can open the app and select the "Font Style" to select "Android Emoji".

Or:

Goto System Settings -> Display -> Font Style then select "Android Emoji"

In samsung device such as galaxy s3 or s2 sometime you find some blank or square for emoji symbols please update system to android 4.04 and above then set font to default in setting. If still don't display emoji symbols please install this font and set font to Emoji in setting.