Vintage cobalt blue glass Pyrex scalloped custard cups.

Pyrex, a brand of heat-resistant borosilicate glass cookware and bakeware, was introduced by Corning Glass Works in 1915. It quickly became a staple in American kitchens for its durability and versatility. The brand is known for its wide range of patterns and colors, many of which are highly collectible today.

Cobalt blue is a popular and sought-after color in vintage Pyrex, often used for various serving dishes, bowls, and bakeware. These custard cups, with their distinctive scalloped edges, were likely produced during the mid-20th century, a period when Pyrex was at the height of its popularity for both practical use and decorative appeal.