How do I add Emoji smileys?
According to Drupal 7.50 released, Emojis were added as a new feature in 7.50 


  Support for full UTF-8 (emojis, Asian symbols, mathematical symbols)
  is now possible on MySQL
  
  If content creators on your site have been clamoring to use emojis,
  it's now possible on Drupal sites running MySQL (it was previously
  possible on PostgreSQL and SQLite). Turning this capability on
  requires the database to meet certain requirements, plus editing the
  site's settings.php file and potentially other steps, as described in
  the change record.