Hello Smartz12 -- Nice coin! Hungary issued gold trade coinage starting in 1830 and continuing through 1892. Before 1870 the pattern on the coin looked different than the picture, but at 1870 and after Franz Joseph profile appears. The ducats have no denomination, but the forints show their denomination on the reverse.
Be careful for restrikes, which we discuss below. Here are the stats for the three denominations of interest:
DUCAT: 18 mm diameter, 0.111 troy ounces gold
4 FORINT: 10 francs, 18 mm diameter, 0.093 troy ounces gold
8 FORINT: 20 france, 20 mm diameter, 0.187 troy ounces gold
Look up the current value of gold on the Internet. Our favorite place for this is kitco.com. Right now the gold price is $1400 US dollars per troy ounce. But it will be different tomorrow. Look it up for yourself.
You can find the base value of your coin by multiplying the troy ounce weight by the gold price. For instance, a ducat contains 0.111 troy ounces of gold, so the current base value is 0.111 x 1400 = $155.
Coin collectors are willing to pay more that the base value when a coin is in good shape. Here are approximate collector premiums that can be added to the base value.
average circulated: $1000 US dollars added premium value
fully uncirculated: $2500
average circulated: $30
fully uncirculated: $80
average circulated: $50
fully uncirculated: $100
Adding these premium value to the base value gives and approximate price collectors might pay for these coins. If you were selling your coin to a dealer, he or she might pay 20 to 50 percent less than collector price. Dealers must subtract their margin from coins they buy to keep their dealerships solvent.
About Restrikes. Now look at the second picture on this page of the back side of an 8 forint gold piece. Do you see the difference in appearance between the 8 forint and the ducat shown above? The surfaces of the ducat are almost mirror-like. They are so much like a mirror they show black in the photo. The surfaces of the 8 forint show gold in the photo, not black. The difference is that the black ducat is a proof coin and the 8 forint is a regular strike coin.
If you have a proof ducat dated 1870 or 1880, or if you have a proof 4 forint dated 1870, or if your coin carries a UP mint mark, you have a restrike coin, not an original strike. Austria and Hungary practice restriking quite a bit. This means they issue modern coins with old dates. The 1870 ducat in our picture was probably minted in the last half of the 20th century, not in 1870.
One of the most famous restrikes like this is the Maria Theresa Thaler shown at this CoinQuest link.
Gold restrikes are beautiful coins and make great collectibles. They are real coins, not counterfeits, made by legitimate governments. However, they carry little or no collector premium and are worth base value only (or close to it). Unfortunately, coin shysters try to sell restrikes as original strikes to unsuspecting buyers. Don't be one of them!