Dear Rabbi Simon
Does a glass challah board require tevillah [immersion in a mikveh, as is generally required for metal and glass utensils]?
Yes it does, but I would advise without a berachah. In many cases, such an item comes from Israel and may well be Jewish-made (in which case tevillah is not required). But not necessarily, as the workers in the factory may be Arabs (or others). Hence (due to the doubt), I would suggest that it should be immersed without a blessing.
Rabbi Rashi Simon