In addition to the millions of Braided Hair Cents struck for circulation, proofs were also struck for collectors in extremely limited quantities. The sale of these pieces was not regulated until 1857 when 200 proofs were produced, representing the largest number of proof strikings for both the type and denomination. For the type, the lowest mintage of a proof coins was an estimated 20 pieces, a number seen during several years.
No Proofs are known for the first year of issue, as collectors usually bought their new coins early in the year when the old type was still in use. No proofs were struck in 1851 or 1853 either, allegedly due to the lack of demand.
Hairlines are a major problem on these rare coins, which are always in demand in any grade. To identify a proof coin as such extremely good reflectivity in the fields and a strong strike should be noted, along with excellent eye-appeal. Typically, these pieces will be encountered in third party grading holders, identified as proofs.
taken from: http://braidedhaircent.com/