If a minor or gentile immerses one's new utensil in a Mikveh, does this immersion suffice to render the utensil permissible for use with food?
According to all authorities, an adult may allow a Jewish minor who has reached the age of Torah education (seven or eight years of age) to immerse a utensil under the adult's supervision. In such a case, the minor may even recite the Beracha before the immersion.
If, however, a minor claims to have immersed a utensil without adult supervision, then, according to the Ben Ish Chai (Rabbi Yosef Chayim of Baghdad, 1833-1909), the child is not trusted and the utensil still requires immersion. Chacham Ovadia Yosef, however, distinguishes in this regard between metal and glass utensils. With regard to metal utensils, which require immersion on the level of Torah obligation, one should not trust a minor who claims he immersed it. Glass utensils, however, require immersion only by force of Rabbinic enactment, and one may therefore trust the child's claim and the utensil need not be immersed before use.
As for gentiles, one should preferably not allow a gentile to immerse one's utensil on his behalf, because he would thereby forfeit the recitation of the Beracha. One cannot recite the Beracha over the immersion if a gentile immerses the utensil. Therefore, in order not to forfeit the opportunity to recite the Beracha, one should preferably immerse the utensil oneself. However, if a gentile did immerse one's new utensil in a Mikveh in front of the Jew, and even if the utensil fell into the Mikveh by itself, the immersion is effective and the utensil may then be used without an additional immersion.
Summary: One may allow a child who has reached the age of Torah education (7-8 years of age) to immerse a new utensil under adult supervision, and the child may recite the Beracha. If a child claims he immersed a metal utensil privately, the utensil still requires immersion; if he claims to have immersed a glass utensil, it does not require immersion. One should preferably not allow a gentile to immerse one's utensil, but if a gentile did immerse the utensil in front of the Jew, it does not require another immersion.
See Halichot Olam, Helek 7, pages 262-263
