Today Your source for all things celebrity and entertainment. Tina Knowles is one proud grandma! News the 61-year-old fashion designer gushed about her "amazing" granddaughter Blue Ivy Carter , the 3-year-old only child of her daughter Beyoncé and Jay Z . Knowles said the girl is the singer's best friend. PHOTOS: Beyoncé and Jay Z's vacation pics Beyoncé and Jay Z usually leave Blue Ivy at home when they go to celebrity events but often take their daughter with them on vacation.