Since the serial # is a bunch of 9's, I figured it wasn't real. Even if it weighs 4-6 grams, that's probably NOT 4-6 grams of actual gold (that would make this item worth hundreds of dollars, which it is not). More than likely, it's some sort of thin aluminum foil that has been treated with an extremely thin layer of real gold, but not enough to be of any real value. Interesting collectibles and the only people that probably made money are those selling these to begin with; usually the secondary market for these is non-existent. Try taking one of these to a well-known coin or currency dealer and see how much they pay for these... Nothing wrong with collecting them, but the amount of real gold would probably fit on a pinhead...
I just checked at aliexpress.com and you can buy a set of 7 of these for about $10 postpaid. If it was truly 4-6 grams of gold in each one and there are 7 of these in a set, that would be about 28 - 42 grams, or approx. 1 ounce of gold. Gold is currently about $1,200 per ounce. So obviously, these can't truly be solid gold for just 10 bucks! More than likely, the underlying material is a foil of some sort (usually aluminum) that is embossed with the design of the banknote and anodized with actual gold (which may be 24K, but again, the layer of gold is so thin as to not be of any real value...). But, it does make for a neat collectible, but no real aftermarket value, since you can buy these from China for very little.. My 2 Eurocents worth...
Ah, it says so right in the listing: pressed with a special polycarbonate (ie: plastic film). So as I stated, the actual gold that is anodized on here may be 24K gold, but the layer is so thin that if it were melted down it wouldn't amount to more than a couple of cents worth.