<Li> Proof - (PR or PF; numerical designation typically between 40 and 70). Coins specially struck for collectors . Usually mirror - like surface . Sand blast and matte proof in some series . </Li> <P> Mint State (MS) - (Mint state 60 - 70) "Uncirculated" and "Mint State" are terms that are many times used interchangeably . MS 70 is considered a perfect coin . Extremely few regular issue coins are considered MS - 70 although it is common for new, modern bullion coins to be given a grade of MS - 70 . </P> <P> The grading standards are different in different countries . The main standards applied outside the United States are presented in the following table . Coin grading is not an exact science . It is a subjective exercise and depends on the qualification and the experience of the appraiser . Industry leaders were extremely concerned that without a standardized grading system, the rare coin industry could face enormous problems . Therefore, on February 3, 1986 the Professional Coin Grading Service (PCGS) was formed and in 1987 the Numismatic Guaranty Corporation . Both associations have the same goal of grading coins . Other prominent grading organizations are the American Numismatic Association Certification Service (ANACS) and the Independent Coin Graders . The grading is usually done by three independent appraisers . A grading finalizer assigns the final grade of the coin and thereafter the coin is sonically sealed in a protective, inert plastic holder known as "slab". Other associations followed and are at present active . This third - party appraisal of a coin's physical condition, backed by a guarantee, and a national network of reputable coin dealers provided an extremely reliable form of protection for rare coin consumers who could then participate in the coin market with greater confidence . </P> <P> The value of coins depends on their rarity . There are several scales which have been developed for the definition of the rarity of a particular coin . The most common are the "Sheldon rarity scale" and the "Universal rarity scale" "Rarity Scales". "Rarity System". Archived from the original on August 5, 2009 . Retrieved June 3, 2010 . </P>

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