Color Of The 6-Cent Columbian (Scott Stamp #235)?

The online images that I have seen of the 6-cent Columbian stamp (#235) show a stamp that is distinctly purple. The 6-cent Columbian stamp in my album, however, appears to be light blue. (See the attached image.) Is this simply fading? Or do I own a counterfeit stamp?
Thanks for any suggestions!

You cannot say much about colours in online pictures.

Here is an example: https://www.lastdodo.nl/nl/items/11845553-kerstmis.

A print run of 90,000 stamps, or 3,600 sheets of 25 will not show much colour variation, especially with modern computer aided printing.
There are two images. The first is of a cancelled stamp. The second is a scan of my stamp from the "Valores en el Tiempo" book. As you can see, the colours are quite different.

Purple is red and blue mixed, so if the red gets bleached out you can be left with a blue stamp.

There are two colors listed in my Scotts Specialized: 235 purple, 235a red violet. Does anyone have any more information on these issues? I have two distinctive shades in my collection.

Brookman (1967) volume III page 67, says,

"The stamp was printed in various shades of purple, all of which were highly fugitive in nature, and it unfortunately is true that a great many of the copies now available have faded to a very marked degree. Such stamps have often faded down to a dull blue shade. It is remarkable how short an exposure to direct sunlight is necessary to badly fade these stamps. As a matter of fact, very few of the copies now seen can be said to be in a shade that approximates the original shade as issued.

Only a small proportion of these stamps was used on first class mail and the usual cancellation is heavy. Very few interesting cancellations are found on this stamp and most collectors can consider themselves fortunate if they can find a copy with good color that bears any kind of a reasonably light cancel."

Here are 3 of mine in different shades.

As RevCollectort says, "purple is red and blue mixed" and it's also true that the fastest-fading color is red. If you've ever wondered why so many older red cars have faded paint, that's why. Park your red car in the garage or at least in the shade. Over time, purple stamps are likely to fade to blue as the red pretty much disappears. For some, that might lower the value at least a little.

It's presumably UV oxidation. I've got CMYK inkjet prints from the 1980s which are framed and glazed- the glass is pressed against the print surface. The magenta in those would fade within hours when left in direct sunlight. The framed prints, hung in indirect sunlight, don't appear to have faded.

The bottom ledgen looks to have some doubling. You have the stamp in hand so I take a better look at it, as it seems to have some transfer doubling. As to the color what has been said I agree , it is normal for the issue.