I work with these mobile phone companies closely, and even if say, these rumours are true, still, dont expect a top notch quality. Micromax uses extremely cheap plastic as its phone casing, cheap components, cheap quality PCB.
For example:
There is a PTFE layer strip (polytetrafluoro ethylene) below phone with keypads. PTFE is a high end polymer whose resin costs about Rs. 1500 per kg, then add you moulding and fabrication costs.
Phones like Micromax/Lemon/Spice, all use cheap UHMWPE (ultra high molecular weight Poly ethylene) layer strip instead of PTFE, which is used by Nokia, Samsung and other premium mobile manufacturers. Reliance Polymers sells UHMWPE resin for Rs. 165 per kg.
The difference in price between these polymers is about 1000%. If I go into details about the properties of these polymers, it would provide a clear picture, but I wont, I'll just let the price speak for itself.
Another example of cheap material:
Every phone has a PCB (Printed Circuit Board). Now, these PCBs come in a thousand varieties/qualities, all depending on the way they are fabricated. One of the first steps in fabrication of PCB is: before the circuit is drawn/stuck on the metal, it needs to be etched.
Etching can be done by various methods, from manual etching with sandpaper and sodium to High End Plasma Ethcing. Premium mobile phone manufacturers use Plasma Etching, whose machine alone costs minimum Rs. 2.5 crore.
Cheap Chinese (as in micromax et. al) use manual sodium etching with hands and sandpaper.
The quality and finish difference between these two types of ethcing is literally day and night.
The properties, like conductiveness, tensile, Shore D, temperature resistance, water resistance are influenced heavily by etching methods.
Heres the story about these Indian-branded-Chinese phones:
They use extremely cheap materials and phones cost them so cheap I'll make you laugh if I tell you how much % profit they earn. Its DIRT CHEAP for them, its mainly because of ultra cheap quality materials 'inside' the phone, which the common man ignores.
Thus, no matter what Micromax says about its phone, I know they're junk, whatever the specs, and I advise you all to not buy them, since they arent quality products. Yes, they do solve the purpose in Tier 2 cities and villages, but if you can afford a phone from a premium company, please do.