In the late 1720’s, Spanish King Philip V decided to modernize the coinage of his New World colonies. New types were ordered for both gold and silver, and machine production was mandated to replace the hand-struck cob coinage. Mexico premiered the new coinage in 1732, striking portrait gold and silver in the very attractive pillar or columnarios design. On the reverse of reales with the columnarios design, crowned twin globes sit between ornate pillars or columns. The globes are meant to represent the Old and New World conjoined, and the legend reinforces the visual imagery. “Utraque Unum” it says. Both are one. Bourbon Spain and her New World colonies are one nation under the Spanish Monarchy.
The coin was actually made in Mexico (testified by the "Mo" acronym on the coin) and consists to 90.7 % of silver. It's value at the time was "8 Reales" (cf the number 8 on the right-hand portion of the coin).

Master assayer Manuel de Leon (M), who had been in office since 1733, retired at the end of 1763 and was replaced by Francisco Antonio de Pena y Flores (F). Thereafter, the pillar coinage of Carlos III bore the assayer combination MF until 1770, the penultimate year of the coinage. (cf the acronym MF on the left-hand portion of the coin) .This issue, Gilboy M-8-44 is the premier issue of assayer Flores.

King Philip V was afflicted by fits of manic depression and increasingly fell victim to a deep melancholia. His second wife, Elizabeth Farnese, completely dominated her passive husband. She bore him further sons, including another successor, Carlos III of Spain, who is mentioned on my coin. Philip died on 9 July 1746 in El Escorial, in Madrid

Carlos III,( 20 January 1716 – 14 December 1788) was the King of Spain and of the Spanish Indies from 1759 to 1788. This fits with the year 1764 imprinted on my coin. Carlos was the eldest son of Philip V.