The Gemara tells that when the Kohen Gadol would enter the Kodesh Ha’kodashim for the special Yom Kippur service, he would wear white garments, rather than his usual gold garments. The reason, the Gemara explains, is "En Kategor Na’asa Sanegor," which literally means, "A prosecutor cannot become an advocate." Gold brings to mind the sin of the golden calf, and is thus a "prosecutor" in the sense that it is a sign of our nation’s religious failure. As such, it cannot be worn as the Kohen Gadol serves on Yom Kippur seeking G-d’s forgiveness on behalf of the Jewish People.
The question arises as to whether this applies to our clothing on Yom Kippur, as well. It is clear that Halacha requires wearing fine clothing on Yom Kippur. The prophet Yeshayahu instructs, "Ve’li’kdosh Hashem Mechubad" – that we should give honor to "the sacred [day] of G-d." The Midrash explains this Pasuk as a reference to Yom Kippur, such that it requires honoring this day. As we cannot give honor to Yom Kippur with fine food and drink, we instead show honor by wearing fine clothing ("Kabedehu Bi’ksut Nekiya"). Indeed, many people have the custom to wear white garments on Yom Kippur, and Ashkenazim have the practice of wearing a white robe ("Kittel") signifying the fact that we become pure as the angels. But may one also wear gold jewelry – such as a watch, ring, bracelet or necklace – as part of this requirement to dress nicely on Yom Kippur? Or would this fall under the law of "En Kategor Na’asa Sanigor"?
The Halachic authorities rule that wearing gold on Yom Kippur is forbidden only when it is embroidered on a white garment. As white represents purity, it would be improper to include in such a garment a golden accessory which brings to mind the sin of the golden calf. However, if one wears a gold piece of jewelry, or watch, on its own, then this is permissible.
The Halachic authorities also discuss the question of whether this rule applies also to women. Rabbi Akiva Eger (1761-1837), in his notes to the Shulhan Aruch (610), cites the Tebat Gomeh as asserting that since women did not participate in the sin of the golden calf, women may wear gold jewelry even if it is embroidered on a white garment. There is no concern for "En Kategor Na’asa Sanegor," as there is no possibility of "prosecution," since the woman did not worship the golden calf. By the same token, Kohanim and Leviyim would be allowed to wear gold embroidery on Yom Kippur, too, since the entire tribe of Levi did not participate in the worship of the golden calf. In truth, however, the Tebat Gomeh himself dismissed this argument, noting that if a woman wears gold jewelry on Yom Kippur, this could trigger "prosecution" against her husband, who purchased the jewelry. This is also the view of the Mateh Efrayim (Rav Efrayim Zalman Margoliyot, 1762-1828). Therefore, women, too, should avoid wearing gold jewelry embroidered on a white garment.
It should be noted, however, that the Mishna Berura (Rav Yisrael Meir Kagan of Radin, 1839-1933) rules (610:6) that one may wear on Yom Kippur only jewelry which he or she normally wears during the week. Jewelry which one wears only for special occasions, such as Shabbat and holidays, should not be worn on Yom Kippur, regardless of what it is made from, as this would be inconsonant with the atmosphere of awe and fear that must prevail on this day. One may only wear jewelry that is normally worn on ordinary weekdays, and if it is not gold embroidered in white, as discussed.
This is the ruling of Hacham Ovadia Yosef, as codified in Yalkut Yosef – Yamim Nora’im (p. 335).
Summary: One may not wear on Yom Kippur jewelry that is generally worn only on special occasions, or golden jewelry that is embroidered on a white garment.