The genesis of the 1 Rupee note lies in the World War I where the inability to mint coins forced the then colonial authorities to shift to printing Re 1 notes in 1917.
The last hundred years -- the first note was introduced on 30 November 1917, with the photo of King George V -- have been all but tumultuous for this creation.
The Reserve Bank website says its issuance was discontinued first in 1926 on "cost benefit considerations". It got reintroduced in 1940, only to be discontinued in 1994 again. The little note got back again in 2015.
Even as it has gone through these travails, the Re 1 note has retained many of its unique distinctions, including being called a 'coin' in legal speak. It is issued by the Government of India and not the Reserve Bank, and is the only 'currency note' or an asset, and not a 'promissory note', which is a liability.
Again, unlike other banknotes, this is not signed by the RBI governor, but by the finance secretary.
When introduced, the Re 1 replaced the silver coin, which was the prevalent way of storing value of the princely Re 1.
"Prices of silver surged during the World War I, so they first printed the note with a photo of the prevalent silver coin on it. Since then, every Re 1 note has a picture of the one rupee coin of that year," Girish Veera, a veteran collector from Dadar, central Mumbai, told PTI.
The first note had the signature of three British finance secretaries -- MMS Gubbay, AC McWatters and H Denning -- and every note is signed by the finance secretary, including 18 since Independence, he added.
According to Mr Veera, the Re 1 note has been discontinued twice and underwent design overhauls at least thrice, excluding the modifications, but it remains one of the most sought-after pieces for every collector.
The major overhauls happened in 1940 when the British changed the features, including halving its size, and in 1949 when the government replaced British symbols with official ones of the newly-formed Republic and the last in 2016, with the reintroduction of the note in the current form, he said.
Not surprisingly, so many changes have raised investor interest in the note and some rare notes have fetched tens of thousands in the collectors' market.
The centenary is expected to be a huge draw at the National Philatelic Exhibition starting in the megapolis tomorrow, and Mintageworld, an online museum for stamps, coins and currency notes, is commemorating the occasion by gifting a memento to each visitor.
Mr Veera pitched for the continuance of the little note, saying "when a bigger denomination note says 'I promise to pay the bearer Rs. 500 or Rs. 2,000', what is the most basic thing there, a single rupee! I think every wise government should continue with the note".