The glass with a beautiful, brilliant, multicolor sheen that we call Carnival Glass was first produced in America around 1905 by an upstart new glass company known as Fenton. In the 19th century, beautiful iridized glass by Loetz, Tiffany and other glass houses was highly prized by the wealthy but was far too expensive to be within the reach of working class households. With the development of a new process for iridizing pressed glass, all that changed, and soon this colorful glass graced the tables of nearly every middle class home in the country.
During its heyday, Carnival Glass was produced by several glass houses in America. However, five companies (Fenton, Northwood, Dugan, Millersburg and Imperial) accounted for the majority of the production and patterns. Later producers were in England, Australia, India, Mexico, Finland, Czechoslovakia, Argentina, Germany and Mexico. In fact, as the popularity of the glass began to wane in the early 1930s, much of the American produced iridescent glass was exported to foreign countries. It was also about this time that the ware was given the name "Carnival Glass." As demand for the glass dropped, companies needed a way to move the glass they had on hand. Seconds were sold to carnivals and fairs to be used as game prizes.
Carnival Glass was made in many colors, but the predominant ones were marigold, blue, amber, red and green. The iridescent sheen was achieved by treating the surface of the glass with metallic salts. Often the iridescence will mask the base color of the glass. If you look at the photo of the rare Grand Thistle water set (http://www.auctionbytes.com/images/grandthistle.jpg), you will see that each piece appears to be a different color due to the way the light plays on the iridescence. However, each piece is made of the same deep, rich amethyst colored glass.
To determine the color of a piece of carnival glass, one needs to look through the piece toward a light source. The color that can be seen when viewing the glass in this manner is base color. The exception to this rule is some marigold carnival glass, which obtains its color from the iridescence being applied over a clear base glass.
Carnival Glass values range from just a few dollars to several thousand, depending upon the item, color, maker, rarity and, most important of all, demand. Values will also vary greatly from one region of the country to another. Common pieces in popular patterns such as Northwood's Grape and Cable will fetch strong prices, while rare pieces in lesser know patterns are very hard to sell at any price. Condition also has a great bearing on prices. Chipped glass will normally bring no more than 10%-25% of the value of a mint piece, and a piece with a crack is nearly worthless in most cases.
There have been reproductions of many pieces over the years. Some of them, such as the items made for L.G. Wright, have become collectible in their own right with a strong following. Some companies, such as Imperial Glass Company and the Fenton Art Glass Company, have also reissued items using the original molds they used during the early carnival glass days. These two companies did mark the newer pieces with their trademarks that are not found on the old glass, so there isn't any danger of confusing the reissues with the old glass. Unfortunately, not all makers have marked the reissued or reproduction items. When buying Carnival Glass, as with any collectible, "Buyer Beware."