I've noticed 1 to 5 gold stars listed my each of the providers when I do a search. Some are grayed out completely even though the provider may have great reviews. What is the significance of the gold stars?

Each star represents 2 ratings points, so someone with 4 gold stars would have an average rating of 8.  The stars only break down into 50% increments so a provider with a 7.76 rating will still have 4 gold stars.

Makes sense. Thanks.