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The markings, 14k & 18k represents the gold purity.
14k means the ring is precisely 58.5% pure gold, while 18k means it is 75% pure gold. Seeing both numbers indicate the ring is a two-tone piece (e.g., your ring is comprised of both 14k and 18k gold)
The letters F J is the designer or makers mark, and stands for "Fancy Jewelry" which is a common maker.
A Crown inside a letter C is a standard European assay or "fineness" mark. This represents the gold content has been tested and guaranteed by an official office in a country with a monarchy (like the United Kingdom).