I don't know what you're budget is, (or what is available in India); however, if you favor dark blues, you can NEVER go wrong with Visconti Blue. For a little less money and a little more ink, I'd also recommend Diamine Midnight or Blue-Black, (but be advised that both of these inks lean more to black than to blue).
Also available in India, I THINK, is Quink Permanent Blue - it isn't as rich as Visconti or as dark as Midnight - but it is cheap, readily available and has a nice blue color. What is more, it has EXCELLENT performance qualities. Make sure you do not get Quink Washable Blue - that fades out as you write - much like the stuff you have and do not like.
EDIT: Hopefully others will chime in, because I just recalled from a while back; I think India may not get the good Quink Permanent Blue, there's a couple of different versions of it floating around I think. If you can get the one that is made in France, go for it.
Hope this helps.
All the best,
Edited by corniche, 09 September 2013 - 08:20.