Men's sterling silver Kali Black Sapphire Square-Top Ring by John Hardy. John Hardy’s Kali Silver Collection is themed after the water-smoothed stones lining Bali's riverbeds. Professional Balian artisans take pure sterling silver and cut it into natural stone shapes. These stone shapes are then set in a free-form pattern on the band to create an organic yet refined look. For a classy centerpiece, 1.50 carats of exquisite black sapphires are embedded in the square top. A traditional form of self-expression, this is a John Hardy classic.