1890–1915
Rock crystal is the name given to all clear colorless quartz also known as pure quartz.
Mikhail Evlampievich Perkhin (Russian, 1860–1903), 1890
Mikhail Evlampievich Perkhin (Russian, 1860–1903), 1896
Mikhail Evlampievich Perkhin (Russian, 1860–1903), 1886