The Loss of an Optic Fiber

The loss of an optical fiber is affected by the wavelength. The light will travel down a fiber until a certain point when suddenly it won't pass light anymore. Once the wavelength gets to a certain level, the loss just shoots back up again. So where's the cheapest place that it makes sense to pick? Oh, just here before that peak. 850 nanometers was chosen because it's the closest place that we've got to visible light.