In ancient times, the Chinese emperors kept Vault Protector coins to bring them good luck/fortune and to protect their treasures. Below is a modern day gold reproduction of the Bao Yuan Vault Protector coin. Undated, 1990 minted, proof China 1+ troy ounce (1 tael) .999 gold Bao Yuan Vault Protector coin (the only 1 troy ounce gold Vault Protector coin minted to date). Early Japanese kobans (c.1600) weighed 18 grams of 842 fine gold. Kobans made in the mid-1800s weighed 11.2 grams of 600 fine gold. And the last koban made in the 1860s weighed only 3.3 grams of 600 fine gold. Below is a modern day reproduction of the 1600's Japan Keicho Koban. 1990 struck BU Japan Keicho Koban. This recently issued Japan Mint Keicho Koban commemorative is an impressive size of 75mm x 38mm and weighs 19.5 grams of pure (9999 fine) gold. They are made in the classic way, hand struck with a number of punches indicating the denomination, authority under which it was issued, the mint and the era during which it was produced.