Just like the nike shoes, they are made in chinese processing branch companies. The nike sunglasses with the signal of "made in china" are real which you take the relax to buy them. However, no matter the quality or the design of these sunglasses are good as those made in foreign countries. The global economy makes them the same.
The headquartered of Nike is near Beaverton, Oregon, in the Portland metropolitan area. Nike is one of the world's leading supplier of athletic equipments including sports sunglasses. I see many Nike shop in China. But i am not sure if there are factory that open in China. With the globalization, i believe there are factory of Nike in China. If you buy them in Nike shop, they are probably real,
Nike sunglasses originally made in USA. However, with the globalization, Nike factory are located oversea, which to meet their market goal and the need of people there. So, if your nike sunglasses are label with a sign" made in china", I think it is real. However, you need not to worry about the quality, because all the nike sunglasses should meet the criterion of its brand expectation. Hope this helpful.