Evolution of collegium system

The Collegium System is a system under which appointments/elevation of judges/lawyers to Supreme Court and transfers of judges of High Courts and Apex Court are decided by a forum of the Chief Justice of India and the four senior-most judges of the Supreme Court.’ There is no mention of the Collegium either in the original Constitution of India or in successive amendments.
How collegium system was born?

First judges case (1982): The court held that consultation does not mean concurrence and it only implies exchange of views
Second judges case (1993): The court reversed its earlier ruling changed the meaning of the word consultation to concurrence. Hence, it ruled that the advice tendered by the CJI is binding on the President in matters of appointment of SC judges. But any such advice would be tendered after CJI consults with two of his most senior-judges. It was also decided in the case that President should appoint the senior-most judge in the SC as the CJI.
Third judges case (1998): The consultation process to be employed should be based on plurality of judges. He should consult a collegium of four senior-most judges before making a recommendation to the President and even if two judges give an adverse opinion, he should not send the recommendation to the President