Mexico 8 Reales 1833 San Luis De Potosí - Damaged

Yes swamperbob, I think it was a button.

I have just done the SG, it is 10.2....Is it due to welding?

The notched rays were caused by a chip in the punch used to punch them into the die. Note that each ray is actually the same.

The lozenge shaped connection point for the stem is rather conclusive. The weld is clear as is the damage to the surface caused by the addition of the stem. There is also some material that has filled between the rays. This added metal along with the heating could effect the density. The weld metal may be a lower density. The heating could volatilize some inclusion (dirt or grease) in the metal which might cause a slight expansion in the size of the coin.

Either of these two could be the cause or even a slight error in weight could make the difference. I would not be too concerned that the coin itself was not original.

The closed C is typical of a punch that has been filed down too far (lapping a process undertaken to remove damage to the cutting surface of a punch or a die).

The way a punch is made enters into this. A typical C punch will not last long if the ends of the opening of the punch are not supported. That means the punch looks more like a C with a bar across the opening when viewed from above.

Here is a rough sketch of what I mean.