Bohemian Glass: Gold Ruby Glass - German/German

In the 18th century, Bohemian glassmakers invented chalk glass. This replaced the thin and easily breakable cristallo glass from Venice. The thick-walled, clear crystal glass was excellently suited for the coloured overlaid glasses that had come into fashion. It was also suitable for the new glass finishing techniques such as glass cutting and glass cutting. The high light refraction and brilliance of the glass was ideal for representing the need for power and splendour at the princely courts of Europe.

Since the beginning of glassmaking, it has been particularly desirable to produce a red translucent glass. The glassmakers took the red ruby gemstone, the "carbuncle", as a model. Albertus Magnus, who lived in the 13th century, considered it the noblest stone because its power was "similar to that of the sun and even in the darkness it was able to glow like coal".

The difficulty in producing red glass lay in the exact composition of the glass mass and the regulation of the fire during the start-up process. Around 1680, the famous glassmaker Johann Kunckel in Potsdam succeeded in melting a translucent red glass made with gold - the precious gold ruby glass. To this day, such glasses are absolute rarities. Only a few glassworks were able to produce gold ruby glass. And the few surviving examples are of inestimable value today.

Incidentally, only a maximum of 0.03 percent gold is needed to turn an initially colourless glass into a purple translucent glass colour by heating it again.

 

Bohemian Glass: Cranberry / Gold Ruby Glass - English

During the 18th century Bohemian glassmakers discovered chalk glass and it replaced the thin and fragile Cristallo Glass from Venice. The thick-walled, clear crystal glass was perfectly suited for glass overlaid with colour that had just come into fashion and likewise for the glass-finishing techniques of cutting and polishing. The high level of light refraction and brilliance of the glass was the perfect representational medium for European courts to demonstrate their power and splendour.

The creation of a red translucent glass was especially coveted since glass production began and glassmakers adopted the red ruby "carbuncle," as their role model. Albertus Magnus, who lived in the 13th century, regarded it as the most precious stone of all, because its power was "similar to that of the sun and the stone was even capable of glowing like coal in the dark". 

The difficulty in producing red glass lay in the exact composition of the glass mass and the control of the fire during initial processing. In Potsdam around 1680 the famous glassmaker Johann Kunckel was able to smelt a red glass that contained gold - the needless to say - valuable, cranberry, or gold ruby glass. This glass is an absolute rarity even today because so few glass foundries were capable of producing cranberry glass and the few examples that still exist are extremely valuable.  

If colourless glass is re-heated, only 0.03 per cent of gold is required to turn it into a crimson-red translucent glass, by the way.