Jean-Baptiste Tavernier, Les Six Voyages
Library of Congress digitized book records
Tavernier was a seventeenth-century jewel merchant whose 1676 travel work is part of the older India-and-diamond-source trail.
Can help prove
Early modern diamond observation, Indian diamond-mine travel context, and diamond-trade context around famous stones.
Be careful
Tavernier does not prove the Habsburg custody chain, Empress Zita's flight, or the Quebec bank vault story.
Use PSF to compare the 1676 French record with later English translations, India/Golconda origin context, the Koh-i-Noor comparison, and modern museum accounts.