A golden highlight for your avatar frame is a nice way to stand out from the rest of the players. It is unlocked at the Sapphire tier of the Loyalty Program. You can read more about our loyalty program and its tiers here.
A golden highlight will appear around your avatar frame once you've activated this feature:
In the chat, your nickname will also get highlighted in gold:
In order to enable the highlight, you need to open your profile by tapping on your avatar and then tap on the "gear" icon:
And tick the highlighted box: