If a casino reorders, and the new chips are indistinguishable from the old chips, except for wear, it's not a variation. If a casino reorders, and the cent sign is done different because the chip manuf. retypesets the hot stamp, it's a variation. If the manuf. has to add a mint mark or state name due to new regulations, it's a variation. If they don't get the colors the same, it's a variation. If a difference is due to a normal manufacturing variation, such as rotation of the inserts to inlays, 3D effects of two semitransparent layers rotated to one another, etc., and in any box of 100 you'll find a random sampling, it's not a variation.

If I CAN SEE THE DIFFERENCE, and we are confident that the difference is due to manufacturing a different order of chips, it's a different chip. If a chip was made the same as it's brother, but now it's different due to fading, chemicals, etc., it's not a variation. If you only have two chips, and there are color differences that could possibly be attributed to environmental issues so you aren't sure, it's not a variation. If you have access to dozens or boxes and some are one color and some are another and none are in between, it's a variation. Bottom line, if we know two chips were made different, and we can tell the difference, they are variations.

That's my opinion. How I decide what to collect as a legitimate variation. I know other collectors who could care less about long and short canes and all that. But a reference guide should include all the knowledge we can possibly fit on the pages. If you don't mind <g>.