【Product Description】 Pyrex was born in 1915 as a household heat-resistant glass product by Corning (founded in 1851), a veteran glass manufacturer that also supplied Edison's incandescent light bulbs. It was named "Pyrex" because the first product made was a pie plate. This is a Pyrex Canada Robin's Egg Blue mug. 【Condition】 Although there are no noticeable signs of deterioration such as scratches or stains from use, this mug has watermarks, which are often seen in this type of product.