Expansion symbol
From M:TG Archive, a library of Magic: The Gathering information
The expansion symbol is used to determine which Magic set a card is from. On the card face, it is located on the right side, in the middle between the illustration and the rules text box.
The color of the expansion symbol indicates the rarity of the card in that particular set. A gold symbol means the card is rare; silver, uncommon; and black, common or basic land. This coloration began with the Exodus set, and previously all expansion symbols were black, regardless of rarity.
Expansion symbols began to be used for base or core sets starting with Sixth Edition. Prior to that, core sets had no symbol and can only be differentiated by the copyright date line or other factors.
