I have a samarium cobalt magnet stuck to my refrigerator that I got from The Foxboro Company when I was coop student there in 1994. It was part of a differential pressure sensor they made that Dutch Oil and others used to measure flow of oil and gas across their empire. A thin wire vibrating in a magnetic field varied frequency as the tension between the sensor diaphragms varied with differential pressure. The frequency was converted to 4-20mA signal for process control. All analog, very precise. This is how we got to the moon girls and boys! The magnets weren't cheap. My magnet has a tiny chip in one edge, so it was rejected and given to me by the engineer that invented and patented the vibrating wire sensor technology. My favorite job evah! and a treasured possession. It's not really suited for refrigerator duty, it sticks too hard.
It was made with California Cobalt, not chinese. But China did the same to our rare earth mines as they did to our steel.