Hello again, Maggie -- We just wrote up our response to your request about an 1887 half eagle. The news on that coin was not particularly good. However, an 1803 eagle is a totally different story. Be careful with your coin, and
NEVER CLEAN A COIN. CLEANING RUINS VALUE.
Capped bust heraldic eagle gold coins come in three denominations: $2.50, $5.00, and $10.00 US dollars. The only significant difference between them is size. The pattern, which is Miss Liberty wearing a cap and a shield-covered eagle with wings spread, is virtually identical for each denomination.
There are gold coins with similar obverses ('heads' sides) but with a small eagle, not a heraldic eagle, on the reverse. The small eagle coins, as shown in the secondary picture, are even more valuable than the heraldic eagle coins, as shown in our main picture. This page applies only to bust heraldic eagle gold pieces.
Here are the sizes of the coins and the total weight of the coins. Weight is a good indicator of authenticity; there are a lot of counterfeits (see below). You need a scale that measures to the nearest 0.1 gram, such as a jeweler's scale.
QUARTER EAGLE $2.50 gold piece, 20 mm diameter, 4.37 grams
HALF EAGLE $5.00 gold piece, 25 mm diameter, 8.75 grams
EAGLE $10.00 gold piece, 33 mm diameter, 17.50 grams
All these coins are very valuable. Fully uncirculated specimens are extremely rare and skyrocket into the stratosphere in value: $10000 to $100000 US dollars. Most coins have some amount of wear from circulation. For undamaged specimens, that is, for coins without scratches, stains, spots, cleanings, gouges, nicks, and the like, these are worth, in general:
worn: $5500 US dollars approximate catalog value
average circulated: $8200
well preserved: $12000
quarter eagles dated 1796 and 1797 are more rare; multiply these values by four
worn: $4500 US dollars approximate catalog value
average circulated: $5600
well preserved: $9000
half eagles dated 1795 are more rare; multiply these values by three
worn: $9500 US dollars approximate catalog value
average circulated: $11000
well preserved: $18000
These are catalog values. Be sure you understand what that means. Use our Important Terminology link to find out. Link is above at left.
As you can see, these coins must be appraised in person. CoinQuest can give only very general guidance. Damage to the coin will render values lower. Subtle minting varieties can have higher values.
About counterfeits, the coin's owner is best qualified to evaluate the chances that a coin is genuine. He or she knows the history of the coin. If it has been in the family for 100 years, it is probably real. If it sold on eBay last week for $10, it is probably fake. Somewhere between these two extremes the truth lies. Counterfeit coins are a real problem in today's coin market. Protect yourself by working with reputable coin dealers, such as those at the PNG Dealers web site.
As discussed above, weight is a good indicator of genuineness. Side-by-side comparisons help sometimes. Check your coin against picture shown here from Bowers and Merena Galleries.