Pure gold coin as in .999 below 1/10 of an ounce I don't know of any. There are coins that have less than 1/10 of an ounce equivalent such as a 2 Peso Mexican coin which can be bought for around $80. Edit: The Perth Mint has 1/20 ounce .9999 gold coins.
how much is a half a gram of gold http://www.perthmint.com.au/catalogue/mini-roo-2013-0-5g-gold-coin.aspx
Here's a super tiny coin! http://www.perthmint.com.au/catalogue/2011-mini-roo-05g-gold-coin.aspx?affiliateID=16 edit: great minds think alike it seems...
I've always wanted to have a few small gold coins, but with gold being priced the way it is, and with high premiums on fractional gold...forget it. Much more coin for your money with silver.
The premium shouldn't really be an issue. Is you are getting a 1/20, you really have to call that collecting as opposed to investing, and if you sell it on the 'Bay you are most likely to get most or all of that premium back from some other collector.
You could look into these... And what makes this coin so neat is that PG won it at the Baltimore show for his expo on the Two cent Piece! That BTW was one of the best exhibits at the show! He spent alot of time and money putting the expo together and IMHO should of taken 1St Place! [/QUOTE]
looking at Ebay has 1/25th oz'ers from Canada Gibraltar Isle of MAN Falklans Islands Fiji most of these get a premium over spot. some of the coins are damaged and get a cheaper price. if you want smaller they have smaller gold bars in 1gram 5gram 10 gram. probably your best bet for lower prices. it cost more to make a 1/20th ozer or a 10th oz'er than it does 1/4th and 1/2 ozers.