Hidden jewels, no matter how radiantly they may shimmer in their cases, can easily get overlooked. That applies to musical jewels as well. One such gem is the Bach Society of St. Louis, which emerges into the public glow just four times a year, most vibrantly in its Christmas Candlelight Concert at Powell.

In between, the group sinks from view. Sunday, March 7, marks their next re-emergence, when the group will offer what is usually a thoughtful and exuberant reading of their Johann Sebastian Bach's majestic Mass in B minor. It happens at 7 p.m. in the warm and gently reverberant acoustics of St. Francis Xavier Church (aka, the College Church) at Grand and Lindell boulevards.

The ensemble, founded by Dr. William Heyne, has been reliably but unobtrusively throbbing near the city's musical life since 1941. Its musical raison d'etre is, of course, to keep alive "the great choral works of the Western tradition." Bach's B Minor Mass and his astonishing St. Matthew Passion are the group's two most-performed masterpieces. But they've also done Mozart and Berlioz and Elgar and Poulenc, and they've commissioned works by composers Stephen Mager (their composer-in-residence), Rene Clausen and Stephen Paulus.

Throughout its history, stability and long-term commitment has been the society's hallmark. Music Director A Dennis Sparger will celebrate his 25th year next season; he is the group's sixth director. Comprised of a chorus of about 60 voices (including 20 paid professional singers), the Bach Society boasts a dropout rate that "is an amazingly low 10 percent."

Nineteen members have sung for more than a decade, another 15 for more than 15 years, and eight for more than 20. Executive Director Alayne Smith has been with the society for 35 years; Gaylene Labore, a phenomenal 55. These singers hail from a remarkable array of day-jobs, among them graphic designer, physical therapist, structural engineer and pediatrician.

Stellar soloists

For this performance, Sparger has, characteristically, engaged soloists that range from local to international. (Those categories often overlap.) The soprano is Sherezade Panthaki, whom the Washington Post has called "a radiant-voiced stand-out." She sang Handel's virtuosic "Gloria" with the Bach Society last April. She has also sung with a wide swath of festivals and companies, from Oregon to Paris, in works by, among others, Mozart, Scarlatti and Bach. She also directs music at the First Presbyterian Church of Urbana, Ill.

Photo courtesy of the Bach Society

The Bach Society at College Church

Sunday's tenor soloist also weds local dedication to national fame. Don Frazure has sung in innumerable venues, from Seattle to Spoleto, in works by Mozart, Verdi, Wagner, Haydn and Prokofiev. (Bach, too.) This Juilliard graduate sang with the Bach Society in both 2007 and 2008, performing in the Beethoven Mass in C and Bach's Christmas Oratorio, respectively. Frazure has received national acclaim and awards, yes, but three years ago he also accepted the position of director of worship at Christ United Methodist Church in Fairview Heights.

Bass Curtis Streetman has performed in numerous European opera houses, has recently debuted at the Theatre Champs Elysees in Paris, and has sung in operas by Mozart, Puccini, Verdi and Handel. His festival appearances range from Tanglewood to Halle; his discography includes Monteverdi and Charpentier. He teamed with Frazure in that 2008 Christmas Oratorio.

The fourth member of this gala roster is Debra Hillabrand, mezzo soprano, the Society's Alto Young Artist. (The Society boasts two more, Soprano Gina Malone and Tenor Joshua Stanton.) She is active with the Washington University Opera, has sung for four seasons with the Union Avenue Opera Theatre, and has also served as Young Artist for both the Wichita Grand Opera and the Central City Opera.

Two homes

The Bach Society has two favorite venues, both warm, inviting and embracing: Powell Hall is home to that radiant Christmas Candlelight tradition. That procession, Executive Director Smith explains, is the "reason everyone comes. The Archdiocesan Children's Choir sings from the balcony, and the Bach Society chorus is on the main floor." The concert draws an audience of more than 2,000 every year, from throughout the region.

Smith also loves the society's other special place, College Church, for reasons both aesthetic and practical. The comparative lack of reverberation "makes the transition from a rehearsal room to the venue a lot smoother. [And] it is such a beautiful space, both acoustically and visually. I feel 'at home'." More down to earth, "the lighting is soft but I can always see my music!" Sparger agrees that it is a great place for "audiences to experience music of spiritual as well as artistic values." Both directors agree that the church is "expertly managed."

Queried about the highlight of his quarter-century career, Sparger insists it occurs "every Monday night when I get to share the world's finest music with many of our region's finest singers." In a few days, St. Louisans who love Bach, or are curious about this musical "summation of Bach's life work," can share that experience.