Gold star = the laws of the state do not note a stance against open carry or that right is specifically protected by statute.
Open carry friendly = OC generally accepted, may require a permit. There also may be other special conditions/restrictions i.e. no OC in bars, banks, municipal buildings, etc. It is the preponderance of these that may keep a state out of the Gold Star category.
Equally important is the reaction of LEA and the courts.
We have no states that have gone "platinum" - allow OC virtually everywhere by LAC.