Proof vs UNC coins

In the recent times of Indian Numismatics, many newbie collectors of late want to know the difference between Proof and UNC coins. The concept is clear with only few people who know it technically. 

First of all to clear the confusion, the term "Proof" and "UNC" are different qualities. 

UNC by definition, an uncirculated coin having mint lustre and shine which are released to the public but not intended for general circulation but is available through a mint. The adjustments are made to the minting process which result in a more proof-like finish. These include using a higher force during coining, the use of fresh dies, and special cleaning. Even a 100 or 200 years old coin having shine are classified as UNC. 

Left Proof  | Right UNC

Proof by definition, Proof coinage refers to special early samples of a coin issue, historically made for checking the dies and for archival purposes, but nowadays often struck in greater numbers specially for coin collectors. Preparation of a proof striking usually involved polishing of the dies. They can usually be distinguished from normal circulation coins by their sharper rims and design, as well as much smoother "fields" – the blank areas not part of the coin's design. The dies for making modern proof coins are often treated with chemicals to make certain parts of the design take on a frosted appearance, with the polished fields taking on a mirror finish. Several other methods have been used in the past to achieve this effect, including sand blasting the dies, and matte proofs. The term "proof" refers to the process by which the coins are made and not to the condition of the coin.  Most proof coins are double struck under higher pressure. This does not normally result in doubling that is readily observable, but does result in the devices being struck fully, resulting in intricate elements of the original die being present on the proof that may not be present in such detail on circulation strikes. After being struck, they are very carefully selected with a selection ratio of less than 20%. There is a higher level of contrast between the raised part and the shallow part in the design of the coin. 

All that being said,  Nearly all countries have issued proof coinage, but following quality parameters by Indian mints during production of the coins is still a question mark. Many times the term proof is highly misused, not only collectors, even government mints too misuse to stringent production process and to charge higher rates.