The color of the name/number is only the color that is used in the slot booth's card printing machine.

It could be changed at any time by any employee in the booth. Some casinos have more than one slot booth and could possibly be using different colors at the same time.

As far as being collectable, I feel that ANYTHING that the casino does to the card will NOT make it a variation. That includes Name/Number variations and the application of stickers.

Only changes made by the card manufacturer qualify as a variation (in my collection).

When in doubt, consult the Well-Lamb book.