色・発色
aventurine
Japanese: アベンチュリン
Gold-brown glass with sparkling crystals of copper and other metals. The luster fades if the glass is overheated.
Learn More
Aventurine is a type of glass that features a sparkling metallic luster and shimmer due to the precipitation of extremely fine metal crystals (primarily copper, gold, and iron) within the glass. Varieties include copper aventurine, which features reddish-brown to golden sparkles; gold aventurine, which has a golden luster; and chrome aventurine (green), among others. It is a glass that replicates the luster of the natural mineral aventurine (sunstone or goldstone).
When using aventurine glass as a fusing material, the metal crystals may dissolve depending on the firing conditions, causing it to lose its sparkle. In particular, high-temperature or prolonged firing can cause the aventurine’s sparkle to fade. Additionally, polishing aventurine glass may reveal the sparkle in the cross-section. We recommend checking how the sparkle changes after firing using a color sample tile beforehand.
Differences from the mineral aventurine
Aventurine is a gemstone and decorative stone formed from natural quartz that contains minute inclusions of mica (such as fuchsite), hematite, and goethite, giving it a unique shimmer.
On the other hand, aventurine glass (also known as goldstone) is created using a technique in which glass containing high levels of copper or iron is slowly cooled, causing the supersaturated metals to precipitate as microcrystals and produce a shimmering effect. Although the two share the same name, they are distinct in both structure and origin.
The term derives from a traditional Murano technique said to have been discovered "per avventura" (by chance) in 17th-century Venice.
Bullseye's Aventurine
The colors sold by Bullseye as “Aventurine Blue (1140)” and “Aventurine Green (1112),” among others, are created using the glass-making techniques described above and are not the minerals themselves. They are art glass made using Bullseye’s proprietary recipe, in which fine copper crystals are precipitated.
Note that crystals are prone to remelting due to overheating (high temperatures or prolonged exposure), which can cause them to lose their sparkle. Avoid prolonged soaking at high temperatures—equivalent to full fusing—and, if necessary, process the crystals within the tack fusing temperature range.
Related Concepts
Be sure to use these in conjunction with metal oxides, coloring versus discoloration, and color sample tiles to understand their behavior through test firings before using them in your actual production.
This entry is written in Japanese by Rei Chikaoka and translated for readers outside Japan. If something reads oddly, the original is the source of truth.