Is there any difference about the value between the onchain and the physical stamp (bought in the online shop with fiat). If yes, how can anyone determine if a stamp is one from the Presale from onchain?
With a code (scratch off!) on the stamp, you can use it to credit a small Ethereum equivalent (in the first issue it was 0.00166666666 ETH, i.e. around 40 cents per stamp) to your electronic purse (the "wallet").
So maybe you have the same value on your onchain and on your physical stamp i guess.
You can use the stamp itself to send mails (7 value)
If yes, how can anyone determine if a stamp is one from the Presale from onchain?
i guess you cant