Altan -- The catalogs list only four very rare pattern (prototype) coins from Heilungkiang Province. The sample in my picture is a 50 cent piece (3 mace and 6 candareens) which sold for $20644 US dollars during a 2020 auction. I cannot find a genuine dollar (7 mace and 2 candareens) in my reference material. However, a Google search produced this fake:
Your specs -- 4 cm, 26 grams, silver -- are about right for a Heilungkiang dollar. The catalogs say the dollar was produced in silver, brass, and silver-plated brass. These would not be magnetic.
There is a possibility that your coin is genuine and, if so, it would be worth many thousands of US dollars. What is its history? Where did you get it? Has it been with you for decades or a few months? If you think it may be genuine, your only choice is to send it to a professional authentication service like PCGS, NGC, or ICG.
DO NOT CLEAN YOUR COIN. CLEANING RUINS VALUE.
Hi Amy --
I hope your coin is real. If you:
1. Check the precise weight (e.g., with a jeweler) and it's close to 26 grams
2. Try a magnet and it does not stick
then your coin may be genuine. The only way to find out for sure is to send it to PCGS, NGC, or ICG (look them up on the Internet) for authentication.