Painting crystal blades
In this tutorial I've used turquoise as the colour of the blade, however it can easily be adapted to any other colour by replacing the colours I've stated with your own. This technique requires smooth blending to achieve the desired effect, which can be achieved in several ways. I personally apply the two colours and then blend in between them, rather than staring at one and finishing at the other. Regardless, I hope you find this tutorial helpful.