We seldom think of South Africa as an operatic diamond mine, yet it has produced some sparklers. The heldentenor Johann Botha, gone too soon. Jacques Imbrailo, a killer Queen of the Night in his boy-soprano days, now a prime-time Don Giovanni and Billy Budd. Latterly Pretty Yende, the toast of Paris, Vienna, the Met. And now the golden-toned Golda Schultz, whose sensuality and spontaneity have impresarios eating out of her hand. Catch her Schubert and Strauss in the intimacy of Weill Recital Hall, Carnegie Hall’s upstairs jewel box. —M.G.