Ron Guth: Prior to 1829, Half Eagles were struck in what is known as an "open" collar -- one which was used more to position the coin than to serve as a third die. This was changed in 1829, when a "close" collar was introduced for the Half Eagles. The close collar produced a uniform diameter on all coins struck thereafter. In order to accommodate the new technology, slight modifications were made to the dies, mostly in the size of the lettering and the shape of the denticles and outer border.
The mintages for this sub-type are higher than for the Capped Bust Left, Large Diameter Half Eagles, but they just as rare. The key to this series is the 1832 with 12 Stars. Though not as renowned as the 1822 or the 1825, it is much rarer than the 1815.
As of May 2011, PCGS had certified only 110 examples of this type. The most frequently seen date is the 1834 Plain 4 (28 certified) while the rarest is the afore-mentioned 1832 12 Stars (1 certified). Almost 65% of the examples certified by PCGS are in Mint State, usually in MS-62 and MS-63. The finest example of this type is a single, monstrous MS-66 1831. Proof examples of this type are exceedingly rare and are not known for all dates.