I'm a bit fascinated with gold. Not only it has fantastic physical and chemical properties but it also shines in a particular way under light, well, it is hard to explain.

So as many people before me every now and then I try to come up with a way to get gold out of seawater. 

In this idea, you would use an X-Ray source to produce rays that when interacting with gold ions, would produce a distinct signature, that you could pick up with a sensor. 

Imagine a flow of seawater, whenever this signature is detected, you open up an aperture and sucks the seawater with gold out of the stream. 

The idea is to repeat this process for a long time, ever concentrating the gold, until it is concentrated enough to be recovered by other traditional methods.