Maran in Siman 301 discusses what items one is permitted to carry in a public domain without an Eruv on Shabbat. One basic principle of these Halachot is that accessories and ornaments commonly worn as jewelry are considered like clothing and may be worn. Therefore, Maran rules that a man may wear a signet ring in the public domain on Shabbat, since that was the type of ring normally worn by men. This is in accordance with the lenient opinion of the Rambam. Rabbenu Tam, on the other hand, is stringent in this case; he is concerned that the man may remove the ring on the street in order to show it off and inadvertently carry it. The Rambam is lenient, because we are not concerned that a man will show off his ring.
However, the Shulchan Aruch prohibits wearing other types of rings, which were not commonly worn by men. The question arises today, when it is common practice for a man to wear other types of rings, such as wedding bands, whether these rings are prohibited to wear in the public domain. The Ran, in his commentary to the Gemara, states that the definition of which rings are commonly worn by men is a function of the societal norm. Based on this, Hacham Ben Sion and Hacham Ovadia rule that any ring specifically made for men may be worn in the public domain on Shabbat.
The Rambam documents a custom for men to refrain from wearing any type of ring whatsoever, including signet rings, in the public domain on Shabbat. In fact, the Magid Mishne comments that he wishes that all communities would adopt that custom. While this is not Halacha, Hacham Ovadia says that one who does so is praiseworthy. In any event, one should be careful not to remove his ring when walking in the public domain on Shabbat.
With regard to pins, the Shulchan Aruch prohibits wearing any type of pin or needle in ones lapel as an ornament in the public domain. However, there is a question whether it is permitted to wear a pin or needle in a functional capacity. For example, may one go out with a pin fastening his cuff or closing a buttonhole? The Beur Halacha (Rav Yisrael Meir Kagan of Radin, 1839-1933), after discussing the issue, leaves the question unresolved.
With regard to a safety pin, the Poskim are lenient, because it is designed to be worn in these capacities. Hacham Moshe Halevi (Israel, 1961-2001), as well as Hacham Ovadia, permit inserting a safety pin in clothing on Shabbat itself.
SUMMARY
1. It is permitted for a man to wear a ring that is commonly worn by men into a public domain without an Eruv on Shabbat.
2. It is permitted to fasten clothing with a safety pin on Shabbat and go out in to a public domain on Shabbat,
