An Ōban was a monetary ovoid gold

Gold

Gold is a chemical element with the symbol Au and an atomic number of 79. Gold is a dense, soft, shiny, malleable and ductile metal. Pure gold has a bright yellow color and luster traditionally considered attractive, which it maintains without oxidizing in air or water. Chemically, gold is a...

 plate, and the largest denomination of Tokugawa coinage

Tokugawa coinage

Tokugawa coinage was a unitary and independent metallic monetary system established by Shogun Tokugawa Ieyasu in 1601 in Japan, and which lasted throughout the Tokugawa period until its end in 1867.-History:...

. Tokugawa coinage worked according to a triple monetary standard, using gold, silver and bronze coins, each with their own denominations.

The first Oban were minted by the Gotō family under the orders of Hideyoshi in 1588.

The Ōban (大判) was equivalent to ten Ryō

Ryo

Ryo may refer to:* The Japanese kana digraph ryo, ryō, or ryoh * Ryō , a gold piece in pre-Meiji era Japan worth about sixty monme or four kan...

s, or ten Koban (小判) plates, with a weight of 165 g.