A recent telephone call from a reader led to this column. He had submitted several Franklin half dollars to one of the major grading services and recently received them back.

He was unhappy with the results and with what he said was the firm’s refusal to explain how the grader reached his conclusions about the grade.

The caller, a collector and subscriber, had expected higher grades for the coins; even more upsetting was that none was certified with “full bell lines,” an indicator that a particular coin is better struck than typical. Franklin half dollars with a full bell line distinction can bring many multiples of what a coin of the same date and Mint, in the same grade, but lacking that qualifier, might bring.

Not surprisingly, the subscriber contacted the firm to ask for an explanation from the grader. He said he was told by the person on the other end of the phone call that the grader stood by his assessment.

Coin grading services have been in operation since 1976. They have done a great if not perfect job of identifying counterfeits, and they have codified grading to a degree unimaginable at the beginning of the 1970s. However, as third-party grading grew to dominate the marketplace, attributes like plus signs and “full bell lines/head/torch/bands” began to play increasingly important roles in valuations. An opinion from a grader or several graders — that a 1953-S Franklin half dollar grading Mint State 65 also has full bell lines — can push the value of a coin from $75 to an astonishing $18,000 or so.

Assessing a coin’s grade is a subjective process, as a coin’s surfaces are compared with a set of standards that each service has defined. Longtime hobbyists know the subjectivity of the grading process can be exploited; cracking a coin out of a grading slab for resubmission in the hopes that it will gain a higher grade is a profitable pastime for some.

We understand both the caller’s desire for an explanation and the grading service’s reluctance to provide one (having to defend a grade for every coin would be time-consuming). The system is not perfect, but it works well most of the time.