The NRC wrote: “Vincent Icke, Professor of Theoretical Astronomy at Leiden University, thinks not. Art and science are two worlds between which many people do not see a link directly,” he says. The doubt is caused by reflections that are visible in the ear jewellery. Icke thinks that it is silver or perhaps polished tin, or even lacked glass.

I think it can also be the same pearl as in the Dutch crown. In the Netherlands is the new king or queen is not crowned but inaugurated and the crown has only a supporting role. It is a refined prop as a symbol of the sovereign power and because it has no leading role, in 1840 Willem II chose for gold-plated silver with cut glass and imitation pearls with a layer of fish scales.

Fischsilber (Silberglanz)
Fish Silver beads exist as glass spheres, on whose inside wall fish scales have been applied and filled with wax as a kind of wax pearls.  Inside the hollow glass sphere with a mixture of fish silver and glue (so-called pearl essence) and then filled with wax, known as Bourguignon pearl or fish bead. Especially made in Paris, Strasbourg, Schwäbisch Gmünd; Vienna, Venice, Lauscha, etc in the 18th and 19th centuries. Fish silver was also used for the iridescent and pearl-like effect in painting’

AvdB

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