Question about acid testing and color results

[bonsai]

I purchased a collar necklace online. seller swore it was acid tested and silver. I tested the inside of the links and it turns bright blue. I told the seller and the seller is now insisting its' b/c they are "oxidized". I believe the item is silver plated.
So my question is is there any circumstance where a real sterling item will turn bright blue on JSP acid test?
Will corrosion/ oxidization affect the results?

[AG2012]

Hi,
On contrary; oxydized silver will show even more intense red colour than freshly filed solid silver.
Regards

[bonsai]

I purchased a collar necklace online. seller swore it was acid tested and silver. I tested the inside of the links and it turns bright blue. I told the seller and the seller is now insisting its' b/c they are "oxidized". I believe the item is silver plated.
So my question is is there any circumstance where a real sterling item will turn bright blue on JSP acid test?
Will corrosion/ oxidization affect the results?

[bonsai]

Hi,
On contrary; oxydized silver will show even more intense red colour than freshly filed solid silver.
Regards

Thank you that’s so helpful!