In 1947, Philadelphia copywriter Frances Gerety scribbled 'A diamond is forever' on a notepad before bed. The four words rewired global marriage customs and were later named the greatest slogan of the 20th century — yet Gerety herself lived alone and never married. The post Frances Gerety, the copywriter who coined ‘A diamond is forever’ in 1947, wrote the line judged the greatest slogan of the 20th century — yet she herself never married appeared first on Space Daily .