Not mine, but this is the smallest coin known is an electrum 1/192 stater, 3mm, 0.06 g. http://www.cngcoins.com/Coin.aspx?CoinID=152972
[h=1]New Discovery: The Smallest Electrum Denomination[/h] Sale: Triton XIII, Lot: 190. Estimate $1000. Closing Date: Monday, 4 January 2010. Sold For $4750. This amount does not include the buyer’s fee. I'm sorry. That is WAY too much money for a barely identifiable fleck of silver.
no pics yet, but i think my smallest coin is a 10mm "Panama pill" I have smaller 2-3 mm silver india coins that i think were hammered or milled ???
I've got one of those flecks of Indian gold... It doesn't look like it would be prohibitive to collect all of the denominations. Maybe one of these days...
It's billed by some dealers as the smallest gold coin in history, at 0.75 grains. I'm inclined to believe it on the grounds that if you made a coin any smaller it would be dust. Whether or not it's authentic is moot - it cost ten bucks.