Buraka Som Sistema are a Portuguese outfit who helped bring kuduro — a grimy electronic music from Angola — to the States last year on "Sound of Kuduro," a frenetic party starter with guest M.I.A. BSS's debut is a nice primer to the genre: chintzy electronics, soca and baile funk beats plus lyrics about blood diamonds and the AIDS crisis. There are moments of pristine beauty: "General" fuses thumping house music with sparkling Afro-pop guitars. After 50 minutes, the buzz wears off — less drum-and-bass grooves would've helped. But Black Diamond is a cool beginning to a new sound.