The Umfaan was introduced in 1997 and, to make the range interesting, a different graphic (which was computer generated, not unique) was machined on the front face of the handle each year. The first 50 Umfaans, which were numbered and marked PP (for pre production) were made in around July of that year, and they had the circle pattern that was colored in a rainbow effect. The next batch, which was made during October/November, had the blue color. The rest of that years production had the circles finished with a light bead blasted finish.
Danbo - I presume when you say the "backside" of your 2001 graphic Umfaan, you mean that 2000 is stamped inside the handle? A concept that is sometimes hard to grasp, if you're not involved in the production side of things, is how long it actually can take from a strip of titanium coming in the door to a finished knife going out the door! We machine handles (and blades) in batches so as to use the machining centers most cost effectively - this might mean that as much as four or six months goes by between the piece being machined and it being decorated/assembled/finished.
Anne