This nice coin, containing 0.1867 troy ounces of gold, is the only 1852 20 francs with inscription LOUIS-NAPOLEON BONAPARTE. There is an 1852 silver 5 francs coin with the same inscription. This page applies only to the gold 20 francs.
To evaluate, first compute the base value of the gold in the coin. For instance, if gold is selling at $1200 US dollars per troy ounce (look it up, it changes every day), then BV = 0.1867 x 1200 = $224. Once you have BV, the catalog values run like this:
average circulated: BV + $10
well preserved: BV + $100
fully uncirculated: BV + $450
Apply the concepts on our Important Terminology page to convert catalog values to actual buy and sell values.