Amberina glass is unique in its range of color shading, morphing across its surface from red to gold and amber. The glass used to make Amberina is known as "heat sensitive" or "heat reactive" glass, which changes color according to temperature. The Amberina shade is achieved by first melting amber glass into its desired shape and then reheating select sections of the piece--usually the top or bottom portion--before it is allowed to fully cool. Amberina glass contains a precipitate of colloidal gold, according to Robin's Nest, which turns from amber to red at the right temperature. Traditional Amberina is red at the top of the piece and amber at the bottom, while "Reverse Amberina" is red at the bottom and amber at the top.
Ruby Amberina Stretch Glass is another form of Fenton's amber color, which was produced by the company from 1917 through the 1920s. This style is often compared to popular metallic finished Carnival Glass, which was manufactured during the same time period. During creation, Ruby Amberina Stretch Glass is sprayed with a mixture of metallic salts before being reheated, according to Fenton Art Glass. This unusual finishing process produces a slightly rough texture and an iridescent luster on the surface, particularly at the edges of the piece.
While there are a wide variety of Fenton art glass styles created in Amberina shades, there are several styles and pieces that are of particular interest to collectors. These include compote fruit bowls, candle sticks, thumbprint goblets, hobnail and hobnob vases and fluted and ruffled vases.
The Fenton Art Glass website provides a wide range of historical literature on the origins and styles of its Amberina shade, as well as links to national and international art glass societies that may be of interest to Amberina collectors.