Impaired Proof Or A Fake?

If it is a fake it is a very good one.
Here are the images from the NGC website, the coin matches perfectly.
http://www.ngccoin.com/price-guide/...-duid-144061

I don't know this series at all, and I am only basing my opinion on the original examples shown in this thread.

When looking at the sellers pictures, the first thing I notice is graininess that jdmern mentions as well as an overall lack of detail; This is always a good indicator of a fake. The second thing is the symbols on the reverse of the coin, they seem thicker and lack the intricacy that is shown on the genuine coins. Look at the symbols with loops for example (Bottom row of symbols on the reverse of the coin); on the genuine coin there is a clear gap, but on the coin you posted these areas are almost completely filled in.

The raised metal abnormalities on the Kings neck, and on the reverse above the symbol that looks like a "T" (Top row of symbols on the reverse) are also concerning.

No good!

Agreed. Those surfaces are questionable in my opinion.

Impaired fake. Obvious signs of a cast counterfeit.

The coin is a numismatic forgery. It is NOT a counterfeit. It was not created to enter circulation at face value. The difference is VERY IMPORTANT and is the basis for value in the area of Counterfeits and forgeries.

There is no requirement to be an expert in a particular series as long as you know what the different modern forgery methods produce. You need to know the "look" of a forgery. You get to know it by looking at numismatic forgeries every chance you get. After a relatively brief time, anyone can learn to recognize the VAST majority of Numismatic forgeries. It is only when it comes to early counterfeits and extremely well made numismatic forgeries that you need an expert.

This coin as noted by John Lorenzo has the appearance of a transfer impression. He saw the same problems that I do. The coin itself is cast. Possibly a centrifugal cast in a plastic mold, typical of the past 20-30 years.

The small raised lumps on the surface of the coin were caused by air bubbles trapped against the mold surface that left small voids. Typical molds used in this process contain multiple impressions (the same or various coins). In this way they produce many minor varieties.

This method also produces images that have lost some to much of the fine detail - and the fields are irregular. This loss of data depends greatly on the casting material used to make the impression. The look is unmistakable once you see it a few times. Since these molds can make a copy of any coin the forgers happen to possess the varieties are endless.

So my advice is simply to get to know what this method produces.
All fakes made from this method will have similar characteristics.

You can then make the diagnosis without having ever seen a genuine issue.