What's a colour you wear after mourn ?
In the culture I was brought up with, not the Iranian culture, people don't have a tacit dress code for funerals. It's not like those funerals where people usually wear black. People wear whatever they like to wear and it's considered totally fine.
You mean at funerals? Where you "mourn" the loss of a loved one? Every is typically draped in black. Can't imagine someone wearing a lime green shirt at a funeral.