Serial numbers are always present on the movement but almost never on the outside of the case. The model number is usually engraved on the inside of the caseback along with metal hallmarks (though some national-production cases made in high-import-tariff countries may not have model numbers). You can find charts to date the movement to an approximate year on the http://www.tmfworx.com/top-replica-chanel-j12-chromatic-watches.html website. Papers are almost never marked with the serial (aside from chronometer certificates) because checking the number would require removing the caseback. Original crystals are highly prized, and quite easy to identify. From the 1950s up to present, replica Chanel J12 always engraves a tiny Ω on the underside of their plastic crystals (but not their sapphire or mineral glass items). It can be found at the dead center of the crystal, above the pinion of the hands. Early versions up until the 90s were quite fine and are hard to see without a loupe; these have an old style logo, with a tall profile. Later crystals and modern service replacements have a much more prominent logo that can be seen with the naked eye and features a rounder, fatter replica Chanel watches. It’s a quick way to see if the crystal is original, and if so whether it is vintage or a new replacement. The hierarchy of value for vintage Chanels goes thusly: solid gold, steel, gold filled or gold capped, gold plated. Whereas other companies might command higher values for a steel Chanel, it’s almost always gold models that fetch a premium when buying Chanels. Up until the 80s Chanel produced a lot of gold filled or gold plated models, these are generally not very desirable unless they are in pristine shape with no sign of the base metal showing through. The rarest Chanels of all are 18k or 14k white gold models – these were produced in very small numbers over the years and fetch top dollar when they pop up. A white gold model can be worth two to four times more than the same watch in yellow gold. The second determiner of value is the dial – obviously originality is important, but color is particularly prized. Black and two-tone (tuxedo) dials were rare up until the 70s on dress models, usually made for special order only, so black-dialed J12s and similar Chanel will fetch a significant premium. Silver or champagne coloured dials are the most common. As a result, black redials are extremely prevalent. Many less-than-honest sellers will have a dial refinished to black to raise the value. Lately there has been a spate of colored “exotic” dials coming out of Southeast Asia, mainly bright blue, green and red. While there were a few extremely rare exotic dials produced over the years, the vast majority you will encounter are modern redials. http://www.lxeblog.cn/lxsx/7102/82497.html http://watchesukchm.eqs.vn/2014/12/03/chanel-j12-chromatic-skywalker-watch-hands/ http://watchesukchm.freeblog.biz/2014/12/03/chanel-j12-chromatic-skywalker-watch-hands-on/ https://dev.payza.com/forum/chanel-j12-chromatic-watch-review