Antique Victorian 935 Argentium Silver Marcasite Blue Glass retailer Brooch

Really lovely antique marcasite cobalt blue glass argentium silver Victorian, possibly Art Nouveau brooch.
1 missing stone.
Stamped 935. (contains 93.5% pure silver with 6.5% alloys, superior germanium replacing some of the copper)
935 silver was primarily used in Europe during the Victorian era.
A little known fact that diamonds were banned from public display in Switzerland during the 18th century.
Also, when Prince Albert died, Queen Victoria required her entire court to wear black and avoid pretentious jewels, hence marcasite became a popular alternative.
Measures almost 1 7/8 x 1 1/8" retailer