I am considering buying an older Boker USA knife but I can't find any info on it. It is a two blade with mother of pearl handles. It is 2 3/4" closed. The tang has Boker USA on one side and 2157 on the other of the main blade. It has no tree brand logo isert. It appears to be rather old. Anyone have any ideas? Is there a web site that you can research older Boker knives? Any info would be appreciated.