Gordon Wrubel: San Francisco Mint 1873 $20. Libs come with Open and Closed 3s. Unlike their Philadelphia Mint counterparts, the Open 3 variety is about three times scarcer than the Closed 3. If you are examining a coin that is not designated, and you do not have the photos above for reference, check the ball on the lower loop of the 3. On the Open 3, the size of the ball is about the same as the opening of the 3 and may just pass through it. On the Closed 3, the ball is too large to pass through the constricted opening. As you can see from the Condition Census listing above, this variety is a rarity in the grade of MS 62 or better.