Best I can decipher, this is a 1,000 Cash brass coin from the T'ung Chih empire. It's slightly bigger than a silver dollar. Do I have this ID'd right, and how do you tell if it's fake? It looks too good to be over 150 years old.
You are correct on the ID of this coin. At least what the characters say. As to whether or not it is real or fake, I can't help you on that. These coins were cast and, at least in the smaller denominations, were made in massive numbers. You can easily find good quality specimens for only a few bucks. Not sure about the higher coin like your 1,000 cash but it wouldn't surprise me if it were legit.
High denomination cash coins of the Qing Dynasty were only produced in reaction to the Taiping Rebellion forcing the Manchu's to even use paper money and grossly devalued cash coins, all denominations for every inscription can be found here. It is a fantasy, Tongzhi tongbao cash coins were only cast in the denominations of 1 wén, 5 wén, and 10 wén, while Tongzhi Zhongbao cash coins were only issued in the denominations 4 wén and 10 wén, this was not because the economy recovered (it didn't until the Guangxu era) but because the Manchu's learned their lesson and market simply didn't accept these unrealistically inflated Xianfeng pieces. It's not uncommon for fantasy pieces to have "a Xianfeng reverse". Later additions (through the "edit" button) below: As you also asked for other reasons why it would be fake I would say that both the colouring and the patina is off for the cash coins from that era.
Thanks for the explanation. I'm still a little unsure by your reference to fantasy pieces, and inflated Xianfeng pieces. Are you saying they're modern fakes, or fakes made during the Qing Dynasty by someone reacting to a period of inflation?
I don't know, fantasy pieced and amulets (for some reason I can't link in the train, so: https://en.m.wikipedia.org/wiki/Chinese_numismatic_charm ) were produced back in the day and today. Xianfeng pieces with high denominations were a real thing, this occured because the state had to cover large military expenses during various crises that occurred during the mid-19th century, under the Tongzhi Emperor the government didn't cast cash coins with denominations higher than 10 wén because even Xianfeng Yuanbao cash coins with face values of 500 wén or 1000 wén were only accepted on the market as 10 wén. The government made high denomination coins during the Qing Dynasty as a means "to pay the troops", as neither the people nor the government would accept "Da Qian" (big money, or cash coins with a nominal value of 4 wén or higher) at their nominal values I would say that this piece is a fantasy, I can't tell if it's contemporary or not but as Qing Dynasty cash coins tended to be made of either yellowish brass with a black interior or brownish brass I'd say that this is a modern fantasy.
Just for the record, this is a real Tongzhi Zhongbao cash coin with the highest recorded nominal value (10 wén): https://commons.m.wikimedia.org/wiki/File:Tongzhi_Zhongbao._10cash._Bao_Yuan.jpg (as I can't seem to insert images in the train through Frisia I posted a link rather than inserting an image.)
I believe I have one here & will try to link to the tread on CT with the photo. https://www.cointalk.com/threads/i-love-big-copper.287898/page-6 You'll have to scroll down; it's the only Chinese coin on the page.
So I believe that I may have found one of these in a California Silver mining ghost town. The coin was found near the inner wall structure of a buildings ruins with was located in an area of town that was known as the Chinese district/street. the coin is heavily weathered and is missing about 25% of it. Only 1 symbol is partially or even remotely discernable and I believe it to identify it as this coin. The coin was surrendered to a park Ranger and will be placed on display in the towns museum and I will be identified as the finder of the coin. Let me know what you think. https://www.instagram.com/p/BuuKVrGnqXS/?utm_source=ig_share_sheet&igshid=wvdy4nvx0vjk