someone told me that oem coils have a marking on the inside of the plug where they draw power.

my coils don't have them - does this mean they're not genuine?

 

See this: https://www.rx8club.com/series-i-tec...s-ebay-247265/

Keep in mind that if they fail the genuine Mazda points noted in that thread, AND you were sold them as Genuine Mazda Brand, then yes, they are fake.

However, there are legitimate coils that don't have the Mazda points on them that are not sold as Mazda.

How they were labeled when you bought them matters just as much as what marks they do or do not have.