Well no, that argument does not work. Apple is the monopolist supplier of iPhones. And it charges whatever price it wants for iPhones. If DeBeers is a sole (or near sole) supplier of a product, then Apple certainly is.
Further, DeBeers must face the same competition that Apple faces. In these comments, we see lots of people looking at other gemstones (sapphires, etc) in place of diamonds. The other gemstone producers compete with DeBeers in the same way that other smartphone producers compete with Apple.
I'm not sure it's helpful to reason from the fact that something is illegal to why it is wrong. Sort of like the joke about the three storekeepers in jail: The first charged higher prices than everyone else and was convicted of price gouging. The second charged lower prices than everyone else and was convicted of dumping and cutthroat competition. The third charged the same prices as everyone else and was convicted of collusion. Laws will be made against all kinds of things, and there are many incentives (e.g. law firms revenue) to make laws against very profitable enterprises.
Further, DeBeers must face the same competition that Apple faces. In these comments, we see lots of people looking at other gemstones (sapphires, etc) in place of diamonds. The other gemstone producers compete with DeBeers in the same way that other smartphone producers compete with Apple.
I'm not sure it's helpful to reason from the fact that something is illegal to why it is wrong. Sort of like the joke about the three storekeepers in jail: The first charged higher prices than everyone else and was convicted of price gouging. The second charged lower prices than everyone else and was convicted of dumping and cutthroat competition. The third charged the same prices as everyone else and was convicted of collusion. Laws will be made against all kinds of things, and there are many incentives (e.g. law firms revenue) to make laws against very profitable enterprises.