The disheartening news is the item is most definitely NOT a slave tag.
By all appearances, I believe the item bears the date of 1950, rather than 1850, and the scratch across the face has altered the numeral "9" to appear as an "8" at first glance. The font (style of letters/numerals) is also 20th Century era.
Furthermore, the only metallic tags or badges ever issued for slave laborers, were from the city of Charleston, South Carolina, and the adjacent burough of Charleston Neck. These "Slave Tags", or Slave Hire Badges are known to be issued from years 1800 to 1865, and carry the city, license number, occupation, and year, in stamped and engraved detail.