When the coins are in this condition it is virtually impossible to tell if they are genuine or if the "wreck treasure" was "salted" with fakes. In the 1970's it was proved that many of the 1733 8 Reales from the Atocha were counterfeit. These coins dated 1782 or 1783 are usually part of the El Cazador treasure. The coins are so porous that their specific gravity ranges from 9.0 to 10.2. Since they are relatively inexpensive and "market acceptable" I would not worry for now until further tests of their actual composition are carried out.
I have no credentials. I bought the coin in the pic some months ago. I thought it looked interesting. It was listed by a seller with lots of coin sales and zero negative feedback. I was, and still am very new to this hobby, and this was bought during a frenzy of late night online auction and Web surfing. I just bought things because I liked them, and now I'm "discovering" coins i had forgotten about. I've never sent anything to a TPG, with no plans to start. I just was looking for some expert opinions.
@Nathan401 I must have transposed your post to read "This is something...and I was looking for more info from you. I have edited my original post to try to answer your questions.
From your images it's hard to tell , when posting look for the small oval button that sez full size images. That way we can enlarge the photo to see it better . 8 reales from the El Cazadore look very similar to yours. They can be found in different grades.
Here's what happened. I have several slabbed ngc shipwreck labels from that wreck. After I bought them, I was disappointed in how the slabs prevented me from touching the "history" of the coins coins, so when I saw this item for sale, I took a chance on it for that very reason. As I said collecting coins was very new to me, and I submitted bids like a madman!
As mentioned, this has the look of a lot of the El Cazador shipwreck, sea-salvaged pieces. But because of those surfaces, it also looks like a cast fake. (I'm not suggesting it IS a cast fake, but when they're all porous like that, even real ones can look fake.) Unfortunately, it's hard (for me, anyway) to tell the difference in this particular case.