My parents are from Argentina and almost everything we have that is
manufactured there has “Industria Argentina” on it, but usually those
pieces are functional objects that are not made of precious materials.
I wonder what the “r p” stands for, it maybe silver plated. Most
pieces I own from Argentina that are silver have the 925 or 900 stamp
or a diamond shape with three ovals inside of it. I would try filing
it in an inconspicous area and see if you notice any change in the
metals’ color or lustre below the surface. I will try to get more of a
definitive answer for you by the end of the week. My parents have
books on Argentinian silversmithing and as well as many pieces so I
will do some research when I visit them tomorrow.