Base silver coin of Tostão D. Sebastião I (1557-1578), with countermark of 120 Reis of D. João IV (Portugal - Law of 3 February 1642), and countermark crowned 200 Réis D. Afonso VI 1656-1667 (Brazilian Law of 22 March 1663, Regiment of 7 July 1663). This type of silver Tostão coin from the 2nd dynasty were controversial coins with an irregular monetary standard in Brazil, as it was a coin that in that colony was circulated at the same time in different places for different values. The stamps of 150 réis and 200 réis were applied to old coins of Tostão according to the value they had in the respective regions, not always complying with the legislation in force (Alvará 6/7/1663 and Regulation of 7/7/1663), taking into account Considering the multiplicity of countermarks  that appear applied to this type of pennies and given the size of the colony and the different places where coins were stamped at the time, some different stamps may have been improvised and applied unofficially in order to avoid the devaluation of the currency.

Portugal silver coin with countermarked of 100 Réis (type III) of D. Afonso VI 1656-1667 Law of March 22, 1663, on, 4 Vinténs Mint Porto of D. João IV 1640-1656, obverse inside pearly circle crown flanked by dots and dot under the mark "LXXX", Legend "D.G.REX.PORTVGALIE.ET.AL", on the reverse inside a pearly circle the Cross cornered by "P", Legend IN.HOC.SIGNO.VINCES", World Coins Portugal KM#426.3 Scarce variant with and without stamp

​

Coin with 250 Réis countermark (rare “2S0” countermark, smaller size, variant type “G”) of King Afonso VI (1656–1667), applied on a Half Cruzado silver coin from Porto mint, of King João IV (1640–1656) — A. Gomes J4.91.11. The legend reads “...REX PORTVGALIE...” with smaller PPPP letters. Reference: World Coins Portugal KM#434.3. There are numerous unclassified and still-studied variants; however, this is the only coin I know of with this specific combination of typological and countermark variants, making it, in my opinion, an example of great rarity.

Coin countermarked with 500 Réis from the reign of King Afonso VI (1656–1667), in accordance with the Law of March 22, 1663, in the Kingdom of Portugal, and with the Royal Decree of July 6, 1663, and the Regulation of July 7, 1663, in the Kingdom of Brazil. This countermark is struck over a silver Cruzado coin from the reign of King João IV (1640–1656). There are several known variants of these countermarks; this example corresponds to the variant bearing the letter “S” instead of the numeral “5,” forming “S00” (World Coins Portugal KM#437). King Afonso VI (1656–1683), known by the epithet “The Victorious,” was the twenty-third King of Portugal. He was born in 1643 and reigned from 1656 until his death in 1683. His wife was Dona Maria Francisca Luísa Isabel d’Aumale and of Savoy. During his reign, coins were minted in copper, silver, and gold, and some of the most emblematic Portuguese coins were issued. However, in this reign only a single coin type was struck in copper, with all remaining issues being in silver and gold.

Portugal, silver coin with 500 Réis Countermark (S00, variant type "E") of King Afonso VI (1656–1683), struck over a silver Cruzado from the Évora Mint during the reign of King João IV (1640–1656) – World Coins Portugal KM#437.2. Coin likely recovered from a shipwreck, as indicated by the presence of saltwater corrosion. King Afonso VI, known as "The Victorious", was the 23rd King of Portugal, born in 1643, and reigned from 1656 until his death in 1683. He was married to Maria Francisca Luísa Isabel of Aumale and Savoy.