AI Appraisal Estimate

This is a hand-colored antique engraved map titled 'CARTE HYDRO-GEOGRAPHIQUE DES INDES ORIENTALES', focused on the coasts of China, Taiwan (Formose), and Southeast Asia. The map is an authentic copperplate engraving, likely dating to the late 18th century, circa 1770-1780, authored by Rigobert Bonne, the Royal Hydrographer to the French King. The piece features a prominent Baroque-style title cartouche in the upper left corner, adorned with ornate scrollwork and garlands. The coastline is highlighted with greenish-yellow professional hand-coloring. Notable geographical features include 'CHINE', 'Isle Formose', and the 'Golfe de la Sonde'. Rhumb lines emanate from a central point, emphasizing its utility as a nautical or hydrographic chart. The paper shows signs of age-related toning, minor foxing (brown spotting), and some faint creasing. The print is contained within a simple double-line border with latitude and longitude markings. A block of French text occupies the upper right quadrant, detailing maritime notes. The overall craftsmanship reflects the high standards of French cartography during the Enlightenment, displaying fine line work and clear typography.

Based on my visual examination of this copperplate engraving, I identify it as an authentic 18th-century hydrographic chart by Rigobert Bonne, likely from his contribution to the 'Atlas de toutes les parties connues du globe terrestre' (c. 1780). The work exhibits the characteristic fine-lined precision of French Enlightenment cartography. The presence of a classic Baroque cartouche and the specific plate's 'hydro-geographique' focus makes it a desirable specimen for collectors of Asian maritime history, specifically for its depictions of Formosa (Taiwan) and the South China Sea. The condition appears fair to good. I note significant age-toning and visible foxing in the upper quadrants, which is typical for paper of this period but slightly suppresses the value compared to a pristine 'washed' example. The hand-coloring is professionally applied and consistent with 18th-century palettes. Market demand for Bonne maps remains stable. While Bonne was prolific, his charts of the East Indies and China consistently outperform his European or American inland maps due to the high interest in colonial trade routes. Recent auction results for similar hand-colored Bonne charts range from $400 to $700 depending on margin health and centering. Limitations: My assessment is based on high-resolution imagery. Full authentication requires an in-person inspection to verify the watermark (e.g., 'bouteille' or 'grappe de raisins'), paper weight, and the presence of a central fold consistent with atlas binding. I would also need to examine the verso for historical annotations or previous mounting residue. Provenance documentation or a record of acquisition from a reputable map dealer would further solidify this valuation.