Component identification (SMD)
My guess is its a 50V 0.1uF capacitor (not tantalum or electrolytic, since there are no polarization markings). 

The J would denote 5% tolerance of the cap.

With no polarization markings it is not a diode or a polarized cap

I couldn't find a company marking or any other 'blue' capacitors, so I'm a little lost as to where this was sourced from. 

Desolder the part from the board and measure it with a 'voltmeter' for impedance and do a capacitance test on it.