In America, "RD" is an abbreviation for "red", a grading-service color designation for copper coins.
RD stands for the color Red in grading copper coins.
Lots of wear on the coin and the lowest grading possible.
edge of a coin with grooved lines that run around the entire perimeter of the coin
In coin collecting, it means Brilliant Uncirculated, a very nice coin, but not as good as a Proof coin.
A coin described as "Premium Quality" is an above average example.
It means the front side the "heads" of the coin. The reverse is the opposite end often called the "tails" of a coin.
A coin collection is called, well, a coin collection. The hobby of collecting coins is called numismatics.
a coin collector
RD is not a coin grade. The letters RD are the abbreviation for the color Red. They usually follow the grade of the coin such as MS-60 Rd. This refers to the overall color of the coins surface, used mostly on 1 cent and other copper coins. Other abbreviation's are: B=brown, RB=Red Brown.
It means "premium quality". It is not an official form of grading.
Coin collecting
While the president has not said much about coin collecting, he has said a lot about education and about the importance of hobbies that are educational. Both stamp collecting and coin collecting teach about geography and about important historical figures, so the chances are, he would be in favor of such hobbies.
A coin which has "circulated" shows evidence of use in commerce, such as luster interruption, wear, circulation marks, dirt, etc. Conversely, an "uncirculated" coin displays no such evidence.