Source: Period sources
Ganga - Jamni refers to the rivers of the Ganges and Jamna. It was used to describe metalwork done in contrasting colors, usually gold and silver in inlay or overlay work, or steel and copper alloy for pieces of mail.1
"It is most common to use only gold or gold leaf for the prominent portions of a work, the sides and back parts being often done in silver, but both metals are frequently employed together with good effect, the silver threading in and out amongst the gold. Such a combination is styled Ganga - Jamni, from its supposed resemblance to the mingling of the dark waters of the Jamna with the muddy stream of the Ganges at the Triveni, or their point of union with the mystic Sarasvati below the fort at Allahabad. Although the Punjab is so prominent for damascening, the most artistic work is done in Rajputana, or wherever the Rajput lives." 2
-Thomas Holbein Hendley, 1892
A mail shirt, probably Punjabi, with rings in contrasting colors.
Sold by Mandarin Mansion in 2019.
1. See: Stone, George C.; A Glossary of the Construction, Decoration and Use of Arms and Armor: in All Countries and in All Times. (Reprint) Jack Brussel, New York, 1961. Page 244.
2. Thomas Holbein Hendley; Damascening on steel or iron as practiced in India. W. Griggs & Sons, Ltd. London 1892. Page 9.