William Claxton Peppe excavated the mound on his estate in January 1898, cutting down through the brickwork to the stone coffer near the base. The bone relics were formally presented by the Government of India to King Chulalongkorn of Siam, who distributed portions to Buddhist communities in Burma, Ceylon and Japan; the coffer and much of the reliquary material entered the Indian Museum in Kolkata. Peppe retained a share of the gems as a finder's portion, and these descended in his family in Britain and later the United States.
Between 1971 and 1977 the Archaeological Survey of India, directed by K. M. Srivastava, re-excavated the stupa. Digging below the level Peppe had treated as the base, the team exposed earlier building phases and, deeper still, two inscribed steatite caskets holding further bone relics. These deeper, stratified finds, now known as the Kapilavastu Relics and held at the National Museum in New Delhi, were read as pushing the primary deposit back toward the pre-Ashokan period and as answering earlier suspicions that Piprahwa might be a later commemorative structure.
In May 2025 the Peppe descendants consigned their gems to Sothebys in Hong Kong. The prospect of a commercial sale of relics associated with the Buddha drew objections from Buddhist organisations, scholars and the Government of India, which asserted a claim to the material as sacred heritage. The auction was stopped; in July 2025 the gems were repatriated through a public-private arrangement, and in January 2026 they were exhibited together in New Delhi for the first time since the excavation.