While this coin is not a great rarity it is notable that it still has the Kurt Prober envelope. This coin was purchased about six years ago on eBay from a seller who was auctioning a number of these pedigree coins, some slabbed, others raw. Kurt Prober, (1909-2008), founder of the Brazilian Numismatics Association, published during his life definitive scholarly references on Brazilian and Guatemalan coinage. Indeed his works, ranging from gold, to silver, to copper coinage, to stamps and Masonic medals ranks him as one of the leading figures in Latin American numismatics in the twentieth century. The envelope shows the detailed Prober's analysis of this coin, to the point of counting the number of jewels on the crown, by row! This coin is KM 307.3 Are there any other 960 reis out there with their Prober envelopes? How about Brazilian and Guatemalan coins with a Prober provenance?
Nice coin! I do see traces of the shield and part of the right pillar from the Spanish colonial 8 reales under-coin. The obverse was struck from a rusted die, with the rust forming raised pinpoint of metal.
