I'd need some time with a catalogue to compare the seal characters for good measure, but this one appears to read clockwise rather than the usual north-south-east-west. The right-hand character is "tei" in Japanese ("di" in Chinese) = Emperor, so dinh in Vietnamese sounds logical. It's just the first, rather blurred character that I can't make out. From the fabric I would originally have said it was Song dynasty Chinese, reading something like Huangdi Yuanbao, though I'd need to check in the catalogue for further attribution.
Martin
NZ
Fifth coin is attributed to Hoang Dinh (1601-1619)
Size is 23 mm.
This one is heavily colored. Could be as a reaction from copper to the glue or to something else.
Bart