Born a brunette, Lucille Ball was turned into a platinum blonde by Hattie Carnegie, the New York designer for whom Lucille Ball modeled in the late 1920s and early 1930s. Carnegie thought Lucy resembled (then-blonde) actress Joan Bennett, a Carnegie client. Her hair remained blonde and became gradually darker (brownish) until she arrived at MGM in the 1940s. It was there that famous hair designer Sydney Guilaroff created the flaming red-orange shade with which Lucy became forever identified. Lucy herself said her career was basically blah until she became a redhead, and then things took off. 

In her book, The Encyclopedia of Hair: A Cultural Study, Victoria Sherrow writes that, “Red hair became more popular in the twentieth century both in Europe and the United States. Some historians say that color films and television [i.e, Lucy?] played a key role, since blond and red shades show up well in those media. Other analysts point out that red hair was often associated with a passionate personality type.” This begs the fascinating question: which came first: Lucy Ricardo’s red hair or her passionate desire to get out of the house and into show business?
- Lucy A to Z by Michael Karol 
(Here shown in Du Barry Was a Lady, 1943)