The earliest surviving (1706) document on Prussian blue's discovery credits Diesbach alone and does not mention Dippel

dye-chemistrypigmentshistory-of-chemistryprussian-blue18th-century-berlinprimary-source-verification

The closest thing to a contemporaneous document behind the Prussian blue discovery story is a handwritten Berlin chronicle, "Kernn aller Fridrichs-Städtischen Begebenheiten" ("Essence of all Friedrichstadt events"). Roth's caption states the entry "was made in 1706"; Kraft's reference list (quoted below) dates the Berger manuscript itself ca. 1730 — so the 1706 date attaches to the chronicle's entry for that year, and whether the surviving copy was penned in 1706 or retrospectively is a tension the two sources leave unresolved. Quoted in translation by Klaus Roth: "A Swiss has […] H. Joh. Jacob Diesbach has invented a certain blue paint and luckily revealed it, which is said to surpass the famous ultramarine; this is why it is now sold under the name Prussian ultramarine or Berlin blue for a reasonable price."

Alexander Kraft's independently peer-reviewed ChemTexts reference list confirms the manuscript is a real, archivally-held document rather than an invented citation: "Berger JE (ca. 1730) Kernn aller Fridrichs-Städtischen Begebenheiten. handwritten manuscript, Berliner Staatsbibliothek Preussischer Kulturbesitz, Ms. Bor. Quart. 124, p 26" (Tier 1 confirmation of the bibliographic fact, source_sha 3a03526d1d3b48ec48bfa94570b0659b478c841f9fc1ab43732b8fe51da4ad86).

This is the single most load-bearing document found in this session's search: it names Diesbach as inventor and records the pigment's early trade names ("Prussian ultramarine," "Berlin blue"), but says nothing about Dippel, cochineal, potash, or any accident mechanism at all. Dippel's role — the vivid, specific part of the popular retelling that the vault's existing note originally carried unqualified — is therefore absent from the earliest surviving trace of the event, not merely under-cited. That absence is consistent with (though it does not prove) the finding in claim-no-contemporaneous-1706-account-survives-for-prussian-blue-discovery that no contemporaneous chemical account of the accident survives at all.