How good is the singing in Marion J. Caffey's "Three Mo' Divas"? Good enough that it takes two top-notch casts of women singers to stage the musical revue, now in its world premiere at San Diego Repertory Theatre.

Created as a companion piece to Caffey's "Three Mo' Tenors" (which was, itself, inspired by the "Three Tenors"), "Three Mo' Divas" is a fast-moving, entertaining and exceptionally well-sung trip through musical history, with an emphasis on black music in America. Caffey's mission is to showcase black opera/Broadway singers, who -- while just as talented as their white counterparts -- are often overlooked by casting directors. And the sextet of talented singers in "Three Mo' Divas" proves these women can hold their own on any stage.

The production begins formally with a quartet of opera arias by Puccini (from "La Boheme," "La Rondine" and "Tosca") and Gounod ("Faust"), then moves into musical theater ("The Wiz," "Ragtime"). There are moving musical tributes to Josephine Baker, Billie Holiday and Lena Horne as well as a fun Cab Calloway number. Then the mood lightens for a Motown girl-groups medley, a patriotic anthem and, finally, a gospel finale.

The show is smoothly produced, well-orchestrated, impeccably sung and dignified. That's the one quibble with the show -- these divas never really let loose (there's a hint of it in the gospel number, but only a hint) -- and you leave the theater wondering how much better "Three Mo' Divas" could be if these wonderful singers unleashed the barn-burning vocals just a bit.

The two casts of "Three Mo' Divas" alternate performances so they can rest their voices for the vocally demanding roles. On some nights, Hope Briggs, Janinah Burnett and Vivian Reed perform, and on other nights, the trio of Henrietta Davis, Jamet Pittman and N'Kenge Simpson-Hoffman perform. To prove the excellence of both casts, San Diego Rep is offering all ticket-holders half-price admission to come see the other cast. My guess is that many showgoers (including myself) will take them up on their offer.

On Saturday night, it was the trio of Davis, Pittman and Simpson-Hoffman who performed. All three are strong singers who balance each other in different ways.

Pittman has the show's best voice, a strong, pure, rich and warm instrument that makes her solos -- particularly "Your Daddy's Son" from "Ragtime" and "Stormy Weather" -- the highlight of the evening. Her vocal control and line are effortless, and her style is refreshing in that she doesn't dress up her singing with cliched vocal tricks.

Simpson-Hoffman, a petite fireball, is the show's all-around entertainer. She sings, she dances and she works the crowd. She's a delight in her audience-interactive "Minnie the Moocher" segment that closes Act I, and she's all sass and shimmying flash as the sexy flapper Miss Celie (from "The Color Purple"). Her voice is thinner and less controlled, but she has a sweet tone with coloratura touches.

Rounding out the cast is Davis, a dramatic soprano who sings all of the heavier operatic numbers. Her technique is on the heavy side, particularly in the "My Man's Gone Now" solo from "Porgy and Bess," where it's difficult to decipher any of her words, but she has power and range. Yet while opera is her specialty, it's with gospel that she brings down the house with a funky, soulful rendition of "The Trouble I've Seen" that leaves the audience shouting "Amen!"

Sprinkled between the solos are several duets and trios. The best is the pairing of Billie Holiday's lynching dirge "Strange Fruit," sung hauntingly by Pittman, while Davis harmonizes wordlessly in a soulful "Lament."

Surprisingly, the one trio that doesn't work is the number that was the high point of Caffey's "Three Mo' Tenors" -- "Make Them Hear You" from "Ragtime." The inspiring anthem brought tears to the eyes when sung with robust power by the tenors, but it sounds oddly sterile in stylized feminine harmony here.

The show's production values are high, with musical direction and arrangements by Joseph Joubert, sets and lighting by Dale Jordan and a parade of fine costumes by Melanie Watnick. The show runs a swift one hour, 45 minutes, with intermission.