Xianfeng Yuanbao, Board of Revenue Mint, Value 100 'Da Yang' Large Specimen

This is a rare and heavy cast copper-alloy cash coin from the Qing Dynasty, specifically issued during the reign of the Xianfeng Emperor (1851-1861). The item is a 'Dang Bai' (Value 100) denomination, commonly referred to as Xianfeng Yuanbao. It measures 55mm in diameter and weighs 61.43g, placing it firmly in the prestigious 'Da Yang' (Large Specimen) and 'Hou Rou' (Thick Body) categories, as standard issues typically weigh between 40-55g. The obverse side (not fully visible but implied by the type) features the four characters 'Xian Feng Yuan Bao' in regular script. The reverse side seen here features the denomination 'Dang Bai' (Value One Hundred) written vertically and the Manchu characters for the Board of Revenue Mint (Boo Chiowan) placed horizontally. The coin exhibits a rich, natural reddish-brown copper tone with significant areas of vibrant green malachite oxidation (patina) accumulated in the recessed fields. The calligraphy is deep and well-defined, indicating a high-quality strike or cast. There is evidence of minor circulation wear on the raised outer rim and high points of the characters, but the structural integrity is excellent with no signs of cracks or modern repairs. The squared central hole is well-formed with clean edges characteristic of mid-19th-century minting technology from the central Beijing mint.

I have conducted a detailed examination of this Xianfeng Yuanbao (Value 100) from the Board of Revenue Mint (Boo Chiowan). The specimen’s physical specifications are exceptional; at 55mm and 61.43g, it sits at the apex of the 'Da Yang' (Large Specimen) and 'Hou Rou' (Thick Body) categories. The copper-alloy composition shows a high-quality cast, with the deep, sharp calligraphy of the 'Dang Bai' characters consistent with early, well-regulated issues from the Beijing central mint. The condition is superior, featuring a desirable 'crusty' patina. The juxtaposition of the rich reddish-brown copper with vibrant green malachite oxidation suggests long-term natural aging rather than chemical acceleration. The square central hole displays the correct 'clean-cut' characteristics of mid-19th-century Chinese minting technology. Market demand for Xianfeng heavy currency is currently at a historic high, with 'Large Specimen' examples commanding significant premiums over standard 40-50g issues. However, a definitive authentication is limited by digital inspection. To confirm the piece is not a high-quality modern 'sur-moulage' (cast from an original), an in-person examination is required to verify the 'ringing' tone of the metal and the microscopic structure of the patina. I would also recommend professional grading by a service such as PCGS or NGC (GBCA for Chinese markets) to solidify provenance. Based on the provided metrics and visual data, this is a highly investment-grade numismatic item that represents the peak of Qing Dynasty currency production.