My opinion on color variations is that two conditions must be met to recognize the variations as collectible and deserving of different TCR numbers:

1. The colors must be easily distinguishable to the eye when the chips are side by side. Scans don't seem to be really conclusive for this comparison; you need to look at the chips themselves in broad-spectrum light (sunlight or light bulbs intended to be broad spectrum).

2. There must be more than one of the alternate color chip found, hopefully a lot of them. This rules out most cases of individual-chip fading and chemical changes to the dyes in the clay.

It isn't uncommon for two batches to differ a bit in color as each is mixed by adding dyes or pigments to the molding compound until they look right to the operator. Even Paul-son color matching samples with the colorname stamped on them have been found to differ significantly.