Should a slight particle of diamond or any other hard stone powder possibly remain on the stone or in the bezel it might eventually enter the end of pivot and again cause pitting. In case that the end stone is of the type that is flat and highly polished on both sides, such as is usually found on detachable dome foreign watches, it can be punched out with a piece of brass wire or peg wood and replaced in reverse position, after which the bezel can be closed and the stone will be just as serviceable as a new one.
Pivots that have been running on pitted end stones are generally rough on the end which is charged with some hard substance. They require special treatment to remove the cause of the pitting and the following method of refinishing is very good. Place the balance in the lathe and draw a soft Arkansas oil stone over the end of pivot with pressure enough to remove a bit of the metal. This will drag out any hard particles that may be lodged in the end and after this has been done the pivot should be pithed clean and polished with a smooth hard steel burnisher covered with oil.
A hard stone such as sapphire or jasper, or a steel burnisher should not be used on the pivot until the Arkansas stone has first done its work, because a hard instrument of this description will force the small particles that cause the pitting further into the end of the pivot instead of removing them entirely.
A pivot that has been treated in this way will not pit the end stone a second time unless carelessness in the use of hard powder permits additional particles to come in contact with the pivot or end stone.
There are some instances in which the steel is highly carbonized but manufacturers generally use the best steel obtainable for balance staffs and excessive carbon can generally be detected with a magnifying glass. Free use of diamond powder and emery wheel dust are more often responsible. The holes of jewels should never be enlarged or polished with diamond powder after the jewels have once been placed in their permanent settings, as this allows the powder to lodge between the jewel and the setting where it cannot be removed by cleaning but where it will be drawn out by the oil and charge any pivot that may be run in the jewel. The grey powder in such instances may be seen through the top of jewel with a strong glass.