While colors and styles of decoration reflected consumer tastes at the time of production, the first thing to look at is the backstamp. On the bottom of most every genuine Pyrex opalware article is an embossed set of markings which contains a variety of information.

Is Pyrex ever unmarked?

Most have blank bases. There is little doubt that the decorated opal bowls are made of pyrex glass. Advertisements and mint-condition items have confirmed that Crown used packaging and stickers to identify unmarked mixing bowls as pyrex glass when they were originally sold.

How do you identify Pyrex?

Use the glass markings, stamps, and logos on the pieces themselves to identify when the glass was produced. The oldest Pyrex markings should be on the bottom of glass pieces and feature Pyrex in all capital letters inside a circle with CG for Corning Glassworks.

Is all Pyrex Bakeable?

Pyrex® Glassware can be used for cooking, baking, warming and reheating food in microwave ovens and preheated conventional or convection ovens. Pyrex Glassware is dishwasher safe and may be washed by hand using non-abrasive cleansers and plastic or nylon cleaning pads if scouring is necessary.

Is vintage Pyrex valuable?

Patterned Pyrex—such as the 1956 Pink Daisy or the 1983 Colonial Mist—also tend to be valuable as a collectors item. Some patterned collections, like the 1959 Lucky in Love heart and four-leaf clover design, have been valued as high as $4,000 for one bowl. But colored Pyrex must look shiny and new.

Is vintage Pyrex worth anything?

Some vintage Pyrex can earn up to $3,000, reports NPR—nevermind that its not dishwasher safe, and its a pain to lug around compared to modern iterations. Sure enough, we found a 1950s set selling for $1,850 on Etsy, and one from 1960 for $700 on eBay. Theres even a rare vintage Pyrex bowl mold going for $1,000.