Lucy was beautiful when she was young. SHE never thought so, though, and said that "Next to Maureen O'Hara, I just look like the hatcheck girl at the Trocadero. I look hard." (or something similar to that. Paraphrasing.) It was Sydney Guillaroff, MGM's hairstylist to all the greats, who died her hair Titian red to give her a more glamorous look. This happened when she got a contract at Metro after leaving RKO, where she earned her "queen of the B's" reputation. MGM put her in some "A" Technicolor films and she did okay (Best Foot Forward, Ziegfeld Follies, Dubarry Was a Lady) but never took off as a big enough star to join the "A" crowd. America knew Lucy, though. And the camera loved her. She was nicknamed "Technicolor Tessie." Peaches and cream skin. Flame red hair. Just stunning to photograph. And a natural comedienne. But she was underused. They just couldn't find the right "formula." Lucy said that she and Eve Arden were the "drop gag girls. We would walk through the room, drop a funny line and then walk out." People laughed at them but they never CARRIED a picture, most of the time.
MGM did not renew her contract in the late 40's, I think it was '48, and so she went to radio to do My Favorite Husband, which was the precursor to I Love Lucy.
She was showing her age BY the 50's, due to a lot of smoking and perhaps the stress of approaching middle age and a wandering bandleader husband who never stopped cheating on her. Karl Freund, a genius cameraman, was hired precisely to, among other lighting miracles (the first time multiple cameras were used in a filmed television show) to make Lucy LOOK as good as possible. She was so pretty as Lucy Ricardo in part due to Freund's incredible lighting. If you look closely at some of the later episodes (say, oh, the trip to Europe ones) you will see a haggard, face lined Lucy in very heavy make-up. Her life was anything but joyous during those years, in spite of America "loving" her. Desi was a drunk, gambling, philanderer who used his "It's my Cuban genetics" as his excuse.
By the time the show ended, the couple was not speaking. Literally. Except for when the cameras rolled. Lucy would say "Would you tell Mr. Arnaz...." and he would do the same referencing her. It was horribly sad and awkward according to those on the set during the final shootings. Edie Adams spoke of it extensively since she and Ernie Kovacs, her husband, guest starred on the very last Lucy-Desi Comedy Hour in 1959. The day after filming wrapped, Lucy filed for a divorce.
Lucy then RAN Desilu (the couple's "empire" company that produced lots of great shows like Star Trek) for several years, and continued smoking. All THAT stress added to her aged face. And then she and Vivian starred in The Lucy Show. In black and white. With good lighting. Lucy banked upon America suspending disbelief of her aging face as long as she could still act like a woman-child and the hot lights would wash out the wrinkles. She actually used face tape to pull up her sagging face and then hid the tape under her big red wigs. She looked like a clown but, then again, she was PLAYING a clown. And clowns are always sad underneath.
Her life has always seemed so sad to me. For all the joy she gave to millions, she really never found her own personal happiness, I don't think. Desi was her one great love and he broke her heart. Gary was a prop.