According to the informant, it is traditional for young newborns to wear clothing and accessories that have the color blue on them for about the first two years of their lives. The idea is that by wearing blue, the weak and helpless infants would be protected from the evil eye, which in Yiddish is known as keyn eyn-hore. This blue protection can come in many forms, including blue clothing and blue jewelry.
The informant, Reyna Babani, is a 71-year-old Mexican Jew who lives in Mexico City. Because she grew up in such a close-knit community, Reyna considers herself an expert on Jewish culture. Although she does not remember who taught this idea to her or when it was learned, she claims that it is a staple of Yiddish culture because everyone she know participated in it. She enjoys this tradition because it helps her feel that the newborn children are safe, especially since they are at such a vulnerable stage in their lives. She also acknowledges that other colors, like red, have been known to work in the past.
What is strange about this tradition is that the color blue has been chosen out of all of the colors that humans can see. Why was blue chosen to protect these children? Why is red not used universally? What other colors are used around the world for a similar purpose? These are questions that would be quite interesting to research.
For more research on the evil eye and Judaism, look here: Brav, Aaron. “The evil eye among the Hebrews.” The Evil Eye: A Casebook 2 (1981): 44-54.