Luke's lightsaber in TESB should be recoloured cyan.

In ANH, when Luke activates his father's lightsaber for the first time we see it with a nice clear cyan glow - totally unlike the azure (sky blue) of Obi-Wan's blade and the later film's saber.

Yeah, it may be have just been a glitch or whatever in the colouring process (like when it appeared white during the training scene aboard the Falcon). However, since it was first revealed with a cyan colour then that colour should take precedence.

Plus, it would add some subtle variety. =D