Carlos IIIi 8 Reals 1809

That alone should tell you that it is fake, and it is all wrong. Especially the date.

petermegally The coin is certainly not real.

What it actually is .... well?

This might be a contemporary counterfeit or a coin made to mix with shipments to China as late as 1890 - 1900. It could also be a modern numismatic forgery. I would rate the odds at 3 to 1 against it being a Class 1 or 2 coin.

If you own it I would like to negotiate a price. Or for a small amount I could review it and provide an opinion. Either way I would love to see the coin in hand.

Based on the engraving I almost asked if the origin could possibly be Egypt. Wish I had now because few will believe that now that I know where you are from. I own a couple that were made in Egypt when this was still a trade coin used for silver value ca 1920. One has definite similarities in the portrait. Makes me like it more.

So it is not a fake piece but a trade coin . But my question is why did they mint it with the 1809 date ?
Note : its weight 22 grams

They were used as trade coins and most were actually made in the 1920s. As was common they were back dated. The reason was that the Carolus dollars of Mexico City were respected as international trade coins in particular in China where they were worth 25-30% more than the silver they contained. The original Carolus dollars were rare by the 1920s so counterfeiters copied them usually from very poor pictures. These are the crudest form of the Class 2 silver counterfeits. The amount of silver in the coin needs to be tested and to avoid modern copies, the coin needs to be tested for improper trace contaminants. I am still very interested in seeing the coin to run appropriate tests.