Oahu’s first Ritz-Carlton Residences will be completed on Oct. 15 with the opening of its 245-room Diamond Head Tower.

The opening of the 38-story tower comes a little more than two years after the opening of the 307-room Ewa Tower. Interior design firm Jon Brent Design and Guerin Glass Architects designed both buildings, which include studio, one-, two-, three- and four-bedroom units as well as penthouses in both towers.  

The Diamond Head tower also adds a second pool to the resort: a 2,900-square-foot…