2700 BC-79 AD

• Cobalt glass was used by the Egyptians, Greeks, Romans, Minoans and Persians in jewelry, decorative vases and even glass boats. Cobalt glass objects were even discovered in Pompeii after the eruption of Vesuvius.
  
  

600-1350

• During the Tang and the Ming dynasties in China, cobalt was used to color vases.
  
  

1470-1650

• Cobalt was discovered in the Schneeberg Mountains in Germany and was also worked from oxides in Burma.
  
  

1730-1780

• Georg Brandt proved the mineral cobalt was the source of the blue color in glass---before then it was believed to have been caused by bismuth. Bergman later proved that cobalt was an element.
  
  

1800s

• Prussian Industrialist Benjamin Wegner ran the Norwegian Blaafarvevaerket, which produced 70 to 80 percent of the world's cobalt blue.
  
  

1930s-1940s

• Cobalt blue was widely used in depression-era glassware. The most popular pieces were made by the Hazel Atlas Glass company.
  
  

Present Day

• Cobalt blue continues to be produced today and antique pieces from the Victorian era through the early 20th century are considered very collectible.