The name"citrine" comes
from the French citron, meaning "lemon,"
and has been used in reference to
quartz that has a somewhat dark yellow
color. Naturally colored citrine has
the dark, blackish color seen in the
photograph on the next
page. However, this material has
never been particularly popular as
a gemstone.
In 1883, the Brazilians discovered
by chance that heating amethyst (purple
quartz) caused its color to change
to a vivid yellow. Because this color
resembles that of the gemstone topaz,
this material was mistakenly called
"golden topaz" for many
years. However, topaz is a completely
different mineral from quartz. Today,
heated amethysts such as those in
the earrings shown below are called
"citrine" and are used as
a jewelry material.
Most amethysts will alter to citrine
when heated to approximately 450°C
(840°F). This heating is considered
an acceptable treatment that brings
out the latent beauty of a stone.
Similarly, most aquamarine is green
beryl that has been treated at temperatures
nearing 420°C (790°F). In both cases,
the treatment is permanent, and once
the color has been altered it will
not revert back to the original. |
The German
city of Idar-Oberstein, located some
120 kilometers (72 miles) west-southwest
of Frankfurt, has long been associated
with citrine and amethyst. Chalcedony,
a variety of quartz, was discovered
in the area in 1497. Later, amethyst
was also discovered there, and the
polishing of both of these materials
continued. A period of decline followed
the playing out of the chalcedony
mines, but in the 1830s, settlers
from Idar who had emigrated to Brazil
began sending chalcedony rough back
home, causing a resurgence of activity.
Motors were used in the polishing
process from about 1900, and the export
of chalcedony, amethyst, and citrine
to various European cities, such as
St. Petersburg in Russia, flourished.
Even now there are about 400 lapidaries
(stone cutters) in Idar, and it is
considered to be among the major colored-stone
polishing centers of the world. Along
with amethyst and chalcedony, citrine
is one of the gemstones that have
helped sustain the city of Idar. |
