Carnival Glass was initially called Iridescent Ware when it was introduced in late 1907. The name carnival glass was not commonly used until collectors in the 1950s began to refer to it as such. This innovative glassware typically featured a vivid metallic sheen of changing hues on pressed glass articles made in highly-patterned moulds. The secret behind the Iridescent Ware was a special spray of metallic salts on the glass while it was very hot.

Carnival glass is made as both functional and ornamental objects. This is an inexpensive pressed glass and found in a wide spectrum of colors. Sometimes glass workers refer this as dope glass because the process of applying the iridescent coloring to the surface is called doping. This was made in over 150 patterns and many different pieces from the year 1907 but 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 a collector's item. Prices of these glasses vary wildly from a few dollars to thousands of dollars. Carnival glass has become antique glass collectible and there is a good 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.

At the time of introduction in late 1907 the carnival glass was called as Iridescent Ware. However, people started using the name carnival only after collectors in the 1950s began to refer to it as such. Among the greatest producers of this type of glass was Millersburg glass Company in Ohio. The first glass products by that company were crystal however the Millersburg plant decided to follow success for iridescent glassware. There is a very active market for this item since it has become an antique glass collectible. So even for an experienced expert this is a hard task.