Q. Can this (chain or necklace) be brought in the bathroom ?
Here are the pictures. Let me know if you need better ones.
Kol tuv.
A. . Horav Shlomo Miller's Shlit”a opinion is that in general one should avoid using psukim for the purpose of adornment or decoration, as it belittles the honor and respect due to the words of Hashem written in our Torah. He added that one cannot say that it is outright prohibited to wear the medallion shown in a bathroom, as the words and letters are not clearly or correctly written. However, the scenario of this question is an additional reason to the one above mentioned, for one that cares and esteems what our Torah is in general and what that particular verse represents, to avoid wearing it at all anywhere.
See also Rabbenu Yerucham (Nesiv 2: 2) Beis Yosef (Y.D. 283) quoting T'shuvas Horambam in regards to medallions with verses from Tehilim worn by children for protection. He asserts that it constitutes a “zilzul” or irreverence to words of the Torah. See also Shulchan Aruch Y.D. (283: 4) regarding the prohibition to weave psukim on a ta'alis and Shach (ibid. 6) that the reason is the zilzul of the psukim of the Torah. (See also Tzitz Eliezer 16: 30)
Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit'a