Either Carlos III (1759-1788) or Carlos IV (1788-1808).
If one real and Carlos III, then coin would date between 1772 and 1789)
If one real and Carlos IV, then coin would date between 1789 and 1808)
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If the coin has a diameter of 20mm, it's a 1 real
If the coin has a diameter of 26 mm, it's a 2 reales from the reign of Carlos III
If the coin has a diameter of 28 mm, it's a 2 reales from the reign of Carlos IV
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