Sonny and Cher once famously sang, “a cowboy’s work is never done.”

With a nod to their ingenious 1972 hit, “The Cher Show” musical, which opened Thursday night at Chicago’s Oriental Theatre, is not quite done. But it’s pretty darn close.

‘THE CHER SHOW’
★★★
When: Through July 15
Where: Oriental Theatre, 24 W. Randolph
Tickets/Info: broadwayinchicago.com

To be clear: The jukebox musical, which serves as a survey of the life of the iconic singer, works on nearly every level. There is a bit of refining still to be done by book writer Rick Elice and director Jason Moore, and a pre-Broadway tryout affords them the time and place to do just that.

In the meantime, “The Cher Show” delivers on its namesake, thanks to a hugely gifted cast, Tony Award-caliber costumes and a veritable hit parade of music. In fact, not since the likes of “Mamma Mia!” and “Jersey Boys” (Elice’s Tony-winning show) has a contemporary musical been blessed with such a rich catalog of hits from which to cull and craft a score.

As for the staging, the show’s opening sequence is a confusing whirlwind of present-day and flashback, with a veritable storm of Chers raining down. That there will be three Chers to take us on the journey is not immediately clear. And the overall backdrop of a variety show taping is sometimes annoying — almost interrupting the storyline — as the musical traverses the years.

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Stepping into the triad role of Cher are three distinct and ridiculously talented actresses. Tony Award nominee Stephanie J. Block (“Falsettos,” “The Mystery of Edwin Drood”), who captivated Chicago audiences during her time here as Elphaba in the first national touring production of “Wicked,” portrays “Star” — that would be Cher, circa the 1980s. Cast as the young California teen Cher called “Babe” is newcomer Micaela Diamond, with Broadway veteran Teal Wicks as the in-between-years Cher, called “Lady.” Elice’s use of the trio as a device to create one complete character is effective most of the time, as the ladies affect Cher’s distinctive contralto to deliver solos, duets and trios of her hits. But it is when each of the three is performing her respective Cher vignettes that they truly dazzle and the show lands on solid footing. Block knocks it out of the park emotionally during one scene where a broke and out-of-work Cher heads to Broadway to jumpstart her career.

The show features more than three dozen songs (courtesy of Daryl Waters’ orchestrations) either in snippets, medleys or their entirety (and out of necessity, not in chronological order), so diehard fans will not be disappointed. What fun it is to hear “I Got You Babe,” sung by Sonny (an effective Jarrod Spector) and his adoring young Cher. Or “Song for the Lonely,” “If I Could Turn Back Time,” “The Way of Love,” “Different Kind of Love Song” “Half-Breed” and “Take Me Home” served up in a sparkling stage production. And Christopher Gattelli’s choreography is marvelous throughout, with dancer Ashley Blair Fitzgerald receiving a well-deserved ovation for her intricate and physically demanding routine during “Dark Lady.”

Nearly stealing the show, however, are the impossibly stunning costumes of Bob Mackie, who has been Cher’s designer of choice since they first met during rehearsals for “The Carol Burnett Show” in 1967. One by one the bedazzled couture parades before us, giving new meaning to razzle-dazzle. The favorites — including her two Academy Award stunners, and dozens more from her world tours and her hit 1970s television series — brought gleeful sighs and thunderous applause from the audience. (Michael Berresse delivers a spot-on portrayal of the Emmy-Award winning clothing designer.) Though CBS censors blushed and demanded less provocative designs from Mackie, Cher’s skin-baring costumes were ratings gold.

For those who are intimately familiar with the story of Cher’s life — her relationship with her mom Georgia Holt (Emily Skinner), “The Sonny & Cher Comedy Hour,” the movie years (including her Oscar-winning turn in “Moonstruck”), and the men in her life outside of Sonny (we get glimpses of Gregg Allman, played by Matthew Hydzik, and Rob Camiletti, portrayed by Michael Campayno) — the storyline will seem second-nature. For those less obsessed with Cher, the pieces of the puzzle may not so easily fall into place.

What emerges from “The Cher Show” is the portrait of an artist — from an insecure teenager who started her career worshipping at the feet of Sonny Bono, to one who gradually and out of necessity emerged as a fiercely independent and strong woman, who realized she was and is second to none. Cher may have sung “All I Ever Need Is You” alongside her beloved “Son,” but truth is, she had all she needed to succeed, deep down inside her. There may not have been a Cher had there not first been a Sonny & Cher. Sonny made a brand out of Cher, but she was born a powerhouse. “The Cher Show” reminds us why America fell in love with the dynamic duo. And why so many will always believe in Cher.

Opening night curtain call for the pre-Broadway premiere of “The Cher Show” musical at the Oriental Theatre in Chicago. | Victor Hilitski/For the Sun-Times