Yes, you are seeing blue on this Glock non-captured recoil spring. Sadly someone thought it would be cool to paint the spring blue. I do not know if the paint can be taken off without taking more of the authenticity of the spring with it. I chose not to try.
Up for sale is a Used Glock OEM 2 piece non-captured) Recoil Spring & Guide Rod (originally called the, "Recoil Spring Tube") for a Gen 1 and/or Gen 2 G17, G17L, G18, G22 and G24. As recoil spring and guide rod are used, they will show signs of age and wear to include the blue paint that someone sprayed on the spring. These are super hard to find and are getting more difficult as the years go by.
The diameter of the guide rod tube is the correct factory specs and measures just shy of 7mm or just a hair over 1/4 of an inch.
I do not have any factory packaging or papers for this item. It will come shipped in a zip lock style plastic bag.
I also have these for the G17, G17L, G22, G19 and G23.... in NOS condition in other listings.
Please see the high resolution photos for condition.
Thank you for looking.