How to display emojis in my app?

I have a Rails 4 app with a comment section. Right now, if I comment with an emoji from an iphone, it just displays as boxes on a computer. How can I get it to appear on a computer screen as a certain image, similar to what Facebook did?

So far, I have a fairly bare-bones comment system:

view

    <!-- form -->
    <%= form_for([@user, @comment], remote: true) do |f| %>
      <%= #... %>
      <%= f.text_area :text %>
      <%= f.submit "Submit" %>
    <% end %>
    <!-- comments -->
    <% @user.comments.each do |comment| %>
      <%= comment.text %><br>
    <% end %>

I'm using sqlite3.