Recently, I purchased three sets of spark plugs. It was part of a couple experiments, one comparing skybox companies and another to compare spark plug performance.
I was concerned about the flooding of our local market with knockoffs, so I ordered a set of Denso Iridium power spark plugs from ebay. Next, I ordered 2 sets from amazon and shipped them using Prime to my two skybox addresses. Both skyboxes notified me of delivery to miami and two days later one set was ready for pickup at piarco, along with the set from ebay.(scratch one skybox...item still not delivered,4 days after I received the set from the competing service).
The set from amazon, on opening the box was poorly packaged and two of the individual boxes were empty, I returned it to the skybox service and they opened a claim(friendly service). I have to mention though, it slipped me to take pictures. The set of plugs from amazon were clearly knockoffs.
Denso Iridium power plugs have a goldish coloured top contact, the set from amazon were highly discoloured and the writing on the plug was partially faded.
The set from ebay was spot on and appear to be genuine; good prints, construction, uniform colour etc.
Still awaiting a set of plugs from amazon, hopefully they wont be fakes... The goal of this post is to give some info on spotting fake spark plugs.