AU means the same thing whether a coin is rare or not: it stands for "Almost Uncirculated". That is, the coin has been in circulation but has been subject to no or almost no wear. AU is one step below uncirculated, and is the highest grade for a circulated coin.
A simple example might be a coin that was supplied by a bank in a roll of new coins, then spent only once or twice and shows no damage or wear.
Almost Uncirculated condition grade better than Extremely Fine not as good as Uncirculated EF > AU > Unc
A certified AU-55 example of the 1879-CC Half Eagle has a current retail value in the $8,000.00 range. This issue saw extensive use and most surviving coins are in the lower grades. AU coins are considered rare.
AU does not stand for anything. There are 3-letter codes for all currencies.
Au, from Aurum, Latin for gold.
On the periodic table, Au represents gold.
G: good VG: very good F: fine VF: very fine EF: extremely fine AU: almost uncirculatedMS: mint condition
au
Gold
I bought most of my rare coins at auctions.
We cannot see you rare coins. Since we cannot even see your rare coins, we do not even know if your coins are indeed 'rare', what they are, their condition, when they were made - we do not know anything. Please specify in a different question what your coin is, the date it was made, and the condition it is in.
Yes, there are rare coins from the Bahamas. One of the coins is a 1991 Bahamas gold coin where only 500 of them were made
AU is an abbreviation for About Uncirculated. It means a coin which is very close to uncirculated by not quite.