Currently, SE employees are given diamonds wherever they need them. I agree with Jeff on this to some degree, employees shouldn't be treated any different.
But... on meta, employees are different. They have the power to dole out official responses, and thus we should be able to differentiate between an employee and a normal user. Currently, only some employees have a diamond on MSO (see http://meta.stackexchange.com/users/178809/stevvve, http://meta.stackexchange.com/users/202998/jeremy-tunnell). This makes it confusing, especially when you see official-sounding posts like this one.
Now, giving diamonds to all employees on meta may not be the best solution to this. I don't think all employees want their precious inboxes spammed with all the suspensions that are doled out on meta, and other mod stuff. They won't really need the diamond powers either (though it wouldn't hurt).
So, I propose this:
Similar to how moderators have "Moderator" clearly on their profile
display "employee" on an employee's profile, along with the diamond if they have one. At least on meta.
It would imho be even better to display it on their usercards in some form, but that has already been shot down.
It would be even even better if non-MSO mods had greyed out diamonds, similar to those on the Area51 flair, but that's just me wanting more shiny stuff ;-)