The apparent meaning of the author’s words is that it is permissible, whether one wears the ring out of need, imitation and custom, or adornment, due to the unrestricted wording.
An example of one who wears it out of need is a person who holds a public office, such as a ruler, an emir, a minister, a director, or the like—someone whose seal is needed by people. Such a person wears it out of need, because keeping it on his finger is safer than putting it in his pocket: if he puts it in his pocket, it may fall out or be stolen.
An example of one who wears it in imitation is what many people do nowadays: one person wears a ring, and another follows his example by wearing one as well. He does not seek adornment, but the people of his town are accustomed to wearing rings, so he wears one.
An example of one who wears it for adornment is a person who wears it to beautify himself. For this reason, he chooses the finest silver in colour, lustre, and form.
Some scholars said that if it is worn for adornment, then it is not lawful, because Allah has assigned adornment through jewellery to women. He, Exalted is He, says: “Is one brought up in adornments, and unable to give a clear account in a dispute?” [al-Zukhruf]. Whatever is distinctive of women is not permissible for men.
The sounder view is that the ruling is general: it is permissible when worn out of need, custom, or adornment.
Indeed, there is no authentic text prohibiting men from wearing silver, whether in the form of a ring or anything else. Rather, it is reported in the Sunan: “As for silver, play with it as you please” (1)—that is, make from it whatever you wish.