Just what you want to see when you click for Callas. Sorry, too many tabs open. Here’s the Puccini, Un bel di, sung by Maria Callas (1954)
http://www.youtube.com/watch?v=hCe00fB5ESI
One of the real heartbreaking arias in all of opera. Puccini likes to write in strange keys. This one is in G-flat Major (or F# Major) if you prefer.