Republican Coin

Start your 'black' collection with it.
Examine the piece closely at 10x, and decide how it was made.

Look for a seam around the rim, which can be an artifact from the making of a two part mold for casting.

Also look for a roundish scar or two somewhere on the rim (a bump or maybe a flat spot with file marks) which would be from the sprue. A sprue is the stem where the metal is poured into the mold during casting. After casting, the sprue is cut off and filed down.

Some legitimate coins have irregularities that look like sprue scars. Those coins began life as strips of flans connected by thinner segments of metal, rather than as individual lumps of metal.

pishpash: buy any fake coin that looks very deceiving,
PROVIDED that
it is sold to you as a fake, and
the price is right.

I wouldn't bother too much with obvious fake coins, unless they have some interesting feature, from which you can learn.

It is by retaining a 'black' collection that you can educate yourself against them.
Examine each one that you have VERY closely, and speak to a professional dealer who has seen many of them, so that you can learn from him.

If it is in ancient coins, have a good look at the
Calgary Coins website.
They have published a very good lecture series on the subject of fake coins.

I have even swapped genuine coins for fake coins with a dealer. Customers sometimes surrender coins to dealers when they realise that a coin that was intended for auction has been shown by the dealer to be a fake. It is from a dealer friend of mine who has an extensive 'black' collection, that some of my 'black' coins have come.

Sometimes, 'black' lots may come up at auction. About 2/3 rds of my 'black' collection has come to me by this way.

Most American gold has been faked, even of common dates. There is quite often a problem with price with gold coins. It is common for fake gold coins to be made of good gold. That means even fake coins can get expensive.
I do not have any fake gold coins in my collection. I baulk at the the price required to buy them, BECAUSE they are often made of good gold.

pishpash:
Sap, one of the resident gurus of the CCF provided most of the answer, in terms of the weight of the coin.
Although I would have liked to see the coin 'in hand', (that's impossible for me), all I have is a bit of experience and a screen picture to look at.
Sap's advice regards weight is the real 'downer' for this piece.

Got it!

Am still non the wiser. I can't see a seam around the edge. It has been cleaned and a fair bit of the bronze is showing through (maybe too much?). The "patina" looks no different from the uncleaned coins I get. I can't find any evidence of a spru, but thats not to say there isn't one there.

Am hoping it is a spanish imitation?

At the beginning of August when we are back from our holiday, I am sending a few coins to the British Museum and will include this. They will try and identify up to 10 coins at one go and just ask that you cover the return postage and a donation is always nice. I don't want to clean it any furthr at this stage.

Seller offered a refund, I said "no thanks". Starting a new page in the album for blacks!

I would be delighted with a Spanish imitation!

When I get the results, I will post here.

Elephant, Yay!

Thanks for that RWS. At 4.8g I thought it was too light not to be an imitation (probably Spanish). The one at the BM is 5.44g so it is not so far out.