Need help on Vietnam coin from my great uncles collection "rare"?

TexasNationals

I have been sorting through some of my great uncles coin collection, he served in the Korean War and 4 tours in Vietnam. He was quite the coin collector and have the 1801-1900 Krause but can not locate this coin. He had quite a collection but this one coin is stumping me. The album was marked Indo-China/Vietnam collection. He had the 2x2's old ones marked such as Thieu Tri 1841-47 and so on. Looks like he has a complete set but what do I know. Anyways one is marked "RARE 1885-1885 HAM NGHI THONG BAO", this coin is the size of a capped bust half dollar maybe a little bigger, made of copper, looks cast, has square hole, the obverse has markings at the north, east, west and south. The revers is plain. It has some green on it as seen on old copper. He had notes about his journeys and the search for coins, not just from Vietnam but many places in south-east asia and other countries. I have no doubt about its authenticity. He also has large collection of paper money. I can find no info on Google other than someone saying it is considered very rare and none were made in gold or silver. Can anyone help me locate this coin in Krause or have an approximate value or history behind this coin that from what I can find was made for only one year

Thanks,

Jeff

TexasNationals

My coin looks very much like this, but in somewhat better shape, It looks like coin #1 but the 2x2 is marked THONG, but the obverse has the same markings and the reverse is plain just like it. Coin #1 It is measures roughly 1 7/8 inches so the Google conversion is right over 46 mm's??

Sapyx

There are no actual lifetime-issue coins listed for this ruler in Krause. And, at nearly 2 inches across, this would definitely classify as an "amulet", rather than a coin intended for circulation, probably made unofficially and some time after he was deposed.

In Vietnam, it's traditional to make large copies of cash coins (or amulets with a cash-like design) and attach them to houses as a good luck charm.