Lot (4) Antique 1860's Czech pierced openwork jet black glass buttons

Lot (4) 1860's Victorian antique Czech handmade jet black glass cabochon pierced openwork buttons. Stunning original buttons, made by creating a metal frame and soldering individual black glass cabochons in place. Finished with black japanning. Extremely rare collectors glass buttons. Some wear to the reverse as seen in the images.

Size: 12 - 14mm 7/16" - 9/16" approximately
Material: Glass. Metal
Shank: Metal loop
Origin: Czech
Year: Vintage cca. 1860's
Condition: Good for age.  
Quantity: 4
The idea of imitating precious jet started in the 19th century. Production of glass "jet" began in the Jablonec area in the 1860's. Originally, the pressed glass was bonded with resin on to a solid metal base. After 1877, Gebruder Feix patented the riveting of glass stones onto metal bases. However, the real revolution came in the 1880's when production began by tin-soldering glass stones with sealed metal tubes on to a wire base. The boom in black costume jewelry making in Czech continued until the turn of the century and by the 1920's had virtually gone out of fashion.