The accepted depreciation is eight pundeyon, which is a rate of two pundeyon per dinar, or one-sixth of a dinar.

The mishna continues: Until when is it permitted for one to return a worn coin once he realizes that it is defective? In the cities [bakerakim], one may return it only until a period of time has passed that would allow him to show it to a money changer, who is an expert in matters of coins. In the villages, where there is no money changer, one may return it only until Shabbat eves, when people purchase their Shabbat needs. Although these are the limits of how much a coin must be eroded in order for there to be exploitation, if the one who gave the coin to the aggrieved party recognized it, he must accept it back from him even after twelve months have passed no matter how little the erosion affected its value. And he has only a grievance against him, as the Gemara will explain.

And one may give the slightly eroded coin for use in the desacralizing of second-tithe produce and he need not be concerned, as one who would refuse to accept a slightly eroded coin is merely a miserly soul, while the coin is in fact valid for any use.

GEMARA: And the Gemara raises a contradiction to the mishna from a baraita in which the same measures of depreciation are enumerated, as in that baraita those measures are introduced with the question: How much must the sela coin be eroded so that its use in a transaction at its original value will constitute exploitation? That is diametrically opposed to the mishna.

Rav Pappa says: This is not difficult. The tanna of our mishna calculates the measures from low to high. The tanna says that it does not constitute exploitation up to, but not including, the levels of depreciation enumerated in the mishna. Beginning with those levels of depreciation, it is exploitation. And the external tanna, i.e., the tanna of the baraita, calculates from high to low. That tanna says that it is exploitation down to and including the levels of depreciation enumerated in the baraita. It is only beneath those levels that it is not considered exploitation. There is no halakhic dispute between the two tanna’im.

The Gemara returns to discuss the mishna and asks: What is different with regard to a sela, that the tanna’im disagree about the level of depreciation that constitutes exploitation, and what is different with regard to a garment, that the tanna’im do not disagree concerning whether the disparity between value and price that constitutes exploitation is one-sixth or less than one-sixth?

Rava said: Who is the tanna that taught the halakhot of exploitation with regard to a garment in the mishnayot cited earlier in this chapter? It is Rabbi Shimon, who maintains that even in the case of a sela, the measure of exploitation is one-sixth. Abaye said that the two cases are different: With regard to a garment, a person is likely to waive the disparity up to one-sixth, as people say: Overpay and acquire an item for your back, i.e., a garment, and acquire at cost items for your stomach, i.e., food. Since it is worth purchasing fine garments, the disparity is not significant. By contrast, with regard to the sela in question, since it does not circulate, he does not waive even the sum of a smaller disparity.

§ With regard to the matter of exploitation and coins itself, the Gemara elaborates: How much will the sela coin be eroded and its use in a transaction will constitute exploitation? Rabbi Meir says: Four issar, which is a rate of an issar per dinar. Rabbi Yehuda says: Four pundeyon, a pundeyon per dinar. Rabbi Shimon says: Eight pundeyon, two pundeyon per dinar. If the depreciation is greater than that, he may sell the coin at its value as metal, not for its original value.

To what extent can the coin erode and it will still be permitted for one to maintain it as a coin? With regard to a sela, it can be used as a sela until it erodes so that its value reaches one shekel, i.e., half a sela. With regard to a dinar, it can be used as a dinar until it erodes so that its value reaches one-quarter. Once it erodes to the point where its value reaches an issar less than that, it is prohibited to spend it. He may not sell the invalidated coin to a merchant, nor to a violent man, nor to a murderer, because they deceive others with it or force them to take it. Rather, he should perforate it and suspend it as an ornament on the neck of his son or the neck of his daughter.

The Gemara continues its analysis of the baraita. The Master said: With regard to a sela, it can be used as a sela until it erodes so that its value reaches one shekel, i.e., half a sela. With regard to a dinar, it can be used as a dinar until it erodes so that its value reaches one-quarter. The Gemara asks: What is different whereby with regard to a sela, it can be used as a sela until it erodes so that its value reaches one shekel, which is half a sela, and what is different whereby with regard to a dinar, it can be used as a dinar until it erodes so that its value reaches one-quarter [rova]?

Abaye says: What is the meaning of rova that the baraita teaches? It too is referring to a coin called rova, which is worth one-quarter of a shekel, which is half a dinar. Rava said: The language of the baraita is also precise in this regard, as the tanna teaches rova and does not teach one-quarter [revia]. The Gemara concludes: Learn from that inference that the reference of the tanna of the baraita is to the coin called rova, which is half a dinar.

The Gemara asks: Why does the tanna state his ruling so that the amount of erosion that disqualifies a dinar is dependent on a shekel? Why does the tanna state the measure as one-quarter of a shekel, rather than stating it as one-half of a dinar? The Gemara explains: By doing so, the tanna teaches us a matter in passing, that there are cases where a dinar originates from a shekel, e.g., a shekel that eroded and is now worth one-half its original value, i.e., one dinar.

This supports the opinion of Rabbi Ami, as Rabbi Ami says: With regard to a dinar that originated from a shekel, it is permitted to maintain it and use it as a dinar. Based on its size and shape, there is no concern that people will confuse it with a shekel. With regard to a dinar that originated from a sela, it is prohibited to maintain it and use it as a dinar. Due to the fact that even after erosion the coin remains the size of a sela, which is clearly larger than a dinar, the concern is that people will mistakenly consider it more valuable than a dinar.

§ The Gemara continues its analysis of the baraita, which teaches: Once it erodes to the point where its value reaches an issar less than that, it is prohibited to spend it. The Gemara asks: What is the tanna saying in that statement? Abaye said that this is what the tanna is saying: If a sela eroded by the amount of an issar greater than the measure of exploitation, it is prohibited to spend it at its original value. Rava said to Abaye: If so, then even any amount greater than the measure of exploitation should be forbidden as well. Rather, Rava said that this is what the tanna is saying: If a sela eroded by the amount of an issar per dinar, it is prohibited to spend it, and this unattributed baraita is in accordance with the opinion of Rabbi Meir, who says in the mishna that the measure of exploitation is one issar per dinar.

We learned in a mishna there (Kelim 12:7): A sela that was invalidated for use as a coin, and an individual designated it so that he would weigh with it items that require weighing, is susceptible to becoming ritually impure. His designation rendered it a vessel like any other weight. To what extent can the coin erode and it will still be permitted to maintain it? For a sela, it is an erosion of two dinars, half its value. If it eroded to an extent that it was worth less than that, he must cut it into pieces to prevent its being confused with a proper coin.

The Gemara asks: If it eroded but its current value is greater than one shekel, what is the halakha? Rav Huna says: If it eroded and depreciated less than one shekel he must cut it into pieces, and if it eroded and depreciated more than that he must also cut it into pieces. Rabbi Ami says: If it eroded and depreciated less than one shekel he must cut it into pieces, and if it eroded and depreciated more than that he may maintain it, because there is no concern that one will confuse a coin that eroded to that extent with a sela.

The Gemara raises an objection from the baraita: