Introduced as Iridescent Ware in 1907, carnival glass acquired that name unofficially from collectors in the 1950s. This marvelous glassware acquired its nickname from the metallic layer on its outside, which constantly changed colors. Iridescent Ware was made in ornately patterned molds, and was sprayed with a mixture of metallic salts before it had started to cool, which allowed for the color-changing effects that gave the glass its fame.

Carnival glass is a colored, inexpensive pressed glass that was used to make both functional and ornamental objects. It can be found in a wide range of iridescent colors. Carnival glass is sometimes called dope glass by glass workers because doping is the process of applying the color to the glass surface. Carnival glass production started in 1907. It was used in production of many different pieces and in more than 150 patterns. However, since it did not command the prices expected, it was subsequently discounted.

The glass is produced in various translucent colors. Primarily amongst these are amethyst, marigold, cobalt, green, and red. Sometimes it is also made in opaque white which is called milk glass. A semi-transparent or translucent pale-green hue was also available before the widespread knowledge of radiation hazards. this glass was called Vaseline or uranium glass. Both of these contain traces of uranium salts which gives the glass a faint green glow when exposed to UV light.

Millersburg glass Company is one of the largest producers of this kind of glass. Crystals were the first glass products of the company. But they decided to go for iridescent glassware to ride the wave of enthusiasm. So, during the early 1910, the line of Radium Glassware was brought out by Millersburg glass Company.

Carnival glass is highly collectable item. Prices vary widely, with some of the pieces worth very little, while other, rarer items command thousands of dollars. It has become an antique glass collectible and there is a very active market for it.

The carnival glass is very difficult to identify. Unfortunately, most of the manufacturers avoid including a maker's mark in their product. Others did so only for part of the time they manufactured the glass. The process of identification involves matching of patterns, colors, sheen, edges, thickness, factors found in old manufacturer's trade catalogs and other known examples, or other reference material. Identifying this glass has become a challenge even to experts since many manufacturers produced duplicates of their rivals' popular patterns.