I\'m trying to figure out why characters like this : 👉 show up like empty boxes. They are unicode characters though and charset is utf-8.
Can it be a font
Missing font characters will usually be substituted with other fonts, and UTF-8 should be able to display all unicode characters. I suspect that the encoding of your file (how it is saved by your editor), does not match the declaration in the meta tags of your HTML page.
You can check your page with this W3-checker, it can possibly give you hints about the problem of your page.
EDIT:
You are right, it's not an encoding problem, the number of the character has such a high number, that the "normal" fonts do not support it. Maybe you can use one of those ☛ ☞, otherwise you would have to use a web font, and fonts with full unicode support can be quite large.