100 Piso Philtrust Bank

Issued to mark the centennial of the Philippine Tuberculosis Society, this commemorative was struck in Nordic gold — the copper-aluminum-zinc alloy developed in the 1990s and widely adopted for high-denomination circulation coins precisely because it resists counterfeiting and discolors slowly. The Philtrust Bank connection commemorates the institution's century of operation, though the coin circulated only briefly before collectors absorbed most of the mintage.