// End color is BLUE, opaque (size is back to 2.5 now.
particles.setEndColor(new ColorRGBA(0, 0, 1, 1));
particles.setEndSize(2.5);
particles.warmUp(60);
final BlendState blend = new BlendState();
blend.setBlendEnabled(true);
blend.setSourceFunction(BlendState.SourceFunction.SourceAlpha);
blend.setDestinationFunction(BlendState.DestinationFunction.One);