Cuchillo Criollo, "Gaucho knife", Brazil or Uruguay ? Age?

[Sajen]

We have seen recently two interesting threads about Cuchillo Criollo.
I have one in my possession where I thought that it is one of this mass produced mid. 20th century ones, fittings from "alpaka", German silver.
Yesterday I noticed that it had become black, so I polished it with a silver cloth and to my surprise the fittings are from silver. The blade is unmarked and slightly flexible. The silver work seems very good to my eyes and by my polishing I noticed a marking on both side ridge of the scabbard, looking to my eyes as there was over a long time a band/belt attached. (last pic.) So I am guessing that it could be older and was in use. And I am unsure if it is a Brazil or Uruguay one.
25 cm inside scabbard, 23,5 cm without, blade 14 cm

Any educated opinions regarding age and origin?