Frost rings are marks which form as a result of freezing temperatures that causes damage to the tender skin of developing fruits, such as apples and pears.
*Russet is the brownish, abnormally rough area on the skin of a fruit. Some varieties of apple actually have a russet naturally russet skin.
Even though this ring isn't very attractive on the finished fruit and we don't put these on our market table, frost rings don't effect the taste of the fruit. These blemished fruits are great for making sauces or cooking with, in general. We used many apples with frost rings in our cider.