Here is one of the better examples of a William and Mary halfpenny from England, dated 1694.
A combination of things makes this piece highly unusual.
Copper pieces were not considered even as real money by the upper classes which ran things in England at the time. That, and the primitive machinery used at the time, made the strikes for this issue incomplete in most cases.
This piece has a much better than average strike for the type.
Also, many pieces from this period appeared to be from cast blanks as opposed to rolled and milled, as stipulated in the terms of the agreement with the outside contractors who made them. My 1694 farthing is an example of a cast piece and has a pitted appearance, not from wear but from the appearance of the blanks used for production.
According to Peck, many pieces from this period are dark due to the presence of sulphur and other impurities in the copper used in production. This piece is not darkly toned.
Lastly the coin has no wear and has nearly pristine surfaces. The auctioneers who sold this piece said it was the best of its type they had ever seen. However there are proof pieces in existence which may have a better appearance than this one. NGC has graded it as an MS 65.
So overall, this is an excellent type piece for the issue.