does one require to tovel porcelain dishes(bone china)? What is the mekor of the psak (machmirim and mekilim)?
Most authorities maintain that porcelain dishes do not require tevillah, according to the strict halachah. The reason is that they have the status of keli cheres, earthenware utensils that are not obligated in tevillah (She’elas Yaavatz 1:67; Pischei Teshuvah, Yoreh De’ah 120:2).
However, the common custom is to tovel the dishes without a berachah (Aruch Ha-Shulchan 120:29; Ben Ish Chai Matos 7).
The reason for this is that the china is treated and compounded with different materials, so that there is a possibility that china dishes are considered glass (which rabinically obligated in tevillah).
Because of the changing ways in which china dishes are treated, it is certainly proper to be careful in this matter, and to immerse china dishes without a berachah.