(n.)
The “terminal point” is the highest possible grade where the cost of submitting a coin to a third-party grading service is still higher than the estimated value on the secondary market of a coin in that grade. Following from this, the next grade lower would cost more to submit (due to grading fees, shipping, etc.) the coin to a grading service than you would likely get by selling the subsequently certified coin.
In their Market Whimsy columns in the February and March 2015 issues of The Numismatist, CoinWeek’s Charles Morgan and Hubert Walker condense the basic premise into the following formula:
Transcribed into English, it states that Terminal Point (T) is the highest grade (G) for an issue where the total cost of acquisition plus certification fees (C) is higher than the price it’s likely to realize when offered on the market (Realized Price, or RP). The second inequality is simply a test to make sure that the grade in question really is the highest grade that meets the criterion for Terminal Point.
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