Corelle cups & mugs of the 1970's, 80's & 90's

Why did they keep changing the cups?

The style and composition of Corelle cups and mugs have been in a constant state of change from the beginning.  All of the closed-handle cups are made of a number of different glass or glass-ceramic materials, and none of them are Vitrelle.  The only cups actually made of true Corelle glass are open-handle stackable cups.  The reason they have open handles is purely out of necessity rather than a designer's whim.

The layered structure providing Vitrelle's incredible strength is also a major drawback for producing a cup that looks acceptable to consumers.  Corelle's manufacturing process involves cutting items from a flat sheet of hot glass, and forming a closed handle is not possible.  To make more conventional cup styles, the compromise has been to turn to other materials and traditional methods.  But some of these choices weren't completely satisfactory either as they did not match Corelle sufficiently in appearance, functionality or performance.

Cup Styles is a guide to the composition and dates of manufacture of Corelle-matching cups and mugs.  Creamers and sugar bowls often share the same shape and composition as cups from the same product line, so cream & sugar sets are also mentioned where applicable.

Backstamps and brand names can be misleading:

Interpreting backstamps is much easier if one remembers that the names on the bottom are just brand names and not an ingredients list.  For example, the composition of the clear Pyrex that was introduced in 1915 (borosilicate) is not at all the same as the opal Pyrex on the market after 1945 (tempered opal soda-lime).  But both were marked with the Pyrex brand name.  More recently, metal bakeware and plastic utensils have been branded as Pyrex, and these items contain no glass at all. 

For identifying cups, the appearance of the glass, coupled with the look and feel of the backstamp is more relevant than the brand name, since this is a function of its composition and method of manufacture.  The same brand name can refer to numerous materials, and the Corning name is the least informative in this regard.  This brand is basically the company's name, and on its own nothing more can be inferred reliably from it.  The Corelle name also is used loosely, motivated by brand cohesiveness rather than the need to inform the consumer of which specific material an item is made.

The following brands can be found on cups made to match Corelle, only one name translates to a single specific material:

Corning:  Centura, Suprema, opal Pyrex, stoneware, real Corning Ware
Corelle:  Centura, opal Pyrex, Vitrelle, stoneware
Corningware:  real Corning Ware, stoneware
Pyrex:  opal Pyrex

START with first cup style.