1954 S Cent Weighs Exactly 2.5 Grams?

Nice looking coin, definitely an error of some kind. Nice find.

That's the route I have been researching, John. I just found these examples of a cent on dime planchet. I'm not saying this is what I have, but there certainly seems there are some similarities. Check these pics out and read the very interesting article of the 1943 cent on dime planchet! Wow, wish I came across that one! lol. Tell me what you think after taking a look. These pics I've attached were from Heritage Auctions.

I'm not sure why he calls the 43 cent struck on a dime planchet as possibly unique, The 43 cent on a dime planchet is probably the most common year for cent on dime planchet errors because they look so similar when new and so were more likely to not get spotted as part of QC. Also that was the only year when the cent and dime had basically the same weight. So that year you had two coins or almost the same weight, diameter, and color and a cent on dime planchet would be almost unnoticeable.

As for the OP coin, I think it looks like it was struck on a rolled thin planchet.

The Mint did strike coins for three other countries in 1954, two in Philadephia and one in San Francisco, but in two cases they were silver alloy coins (900 fine and 835 fine) and the other was in Chromium Stainless steel.

I also checked to see if there was a chance of a foreign planchet left over from 1953 production as a possibility but there were no suitable candidates from 1953 either.

Wow. Thanks for all of the great info, Condor!

And thank you Mr. Mike Diamond, for taking the time to read and your input! Do you suggest hanging on to this coin?

Will do. Thanks John!

I don't think the value would justify the cost of a TPG.
John1

One thing I have found which is easy and I think fun when researching the US Mints schedule I.e minting for other countries and what is going on with our currency is enter the date and then US Mint or sometimes just the date and then mint and click on Google Books. Tons of stuff! Sometimes I think I can almost hear the director, employees, congress bicker through the pages :-) ( only my opinion)