Gem of the Month
Each month this section will feature
either a topic of interest to gem lovers or one special gemstone with
background on the material and its value.
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September,
2000
Citrine
Citrine, yellow to red-orange quartz,
was once the Rodney Dangerfield of the gem world. Its sheer abundance
being responsible for this "no respect" treatment. That has begun to
turn around somewhat in the last couple of decades as fashions have
repeatedly emphasized Earth tones and home shopping networks have
marketed the various shades of citrine aggressively with catchy
adjectives like "butterscotch" and "whiskey" . Actually, very little
of the quartz which is mined is citrine. Natural stones tend to be
pale yellow, often with smoky tones. The vast majority of citrine
which is marketed is produced by heating smoky quartz (produces light
to medium yellows) and amethyst (produces stronger yellows and
orange-red to orangey brown shades). The treatment is usually done
right at the mine, and is stable, and fully accepted within the gem
trade. Recently colorless, rock crystal quartz from certain mines has
been irradiated and heated to produce a neon, slightly greenish
yellow, usually called Lemon Quartz. In the past, it was commonplace
for citrine to be given misnomers such as, "Brazilian topaz", or
"Madeira" topaz, etc. The higher gemological knowledge level of both
jewelers and the public make this practice rare today. This gem is a
fine jewelry stone, with no cleavage and a hardness of 7,
furthermore, its availability in large sizes enables cutters to use
it for dramatic and intricate custom cuts. It is also used for gem
carvings. Stable in light and not very sensitive to chemicals, this
stone requires no special care and can be used for any jewelry
application. Virtually all citrine comes from Brazil.
Value
At the top end of the scale are prime
specimens of the most saturated yellows, oranges and reddish tones.
Those with less intense color fall into lower value ranges with pale
or smokey stones at the bottom . As with any gem material custom
cutting increases value and inclusions decrease it. There is no
exponential increase in value per carat with increase in size as
larger sizes are readily available. In many fancy cut or carved
specimens the majority of the value is due to the artistry of the
fashioning.
Gemological Data:
Makeup: silicon dioxide
Luster: vitreous
Hardness: 7
Crystal structure: trigonal
Cleavage: none
Density: 2.65
RI: 1.54
Birefringence: .009
Dispersion: .013
Stones Currently Available:
{Search
our Catalog}
Go to: Homepage
-- what's new in faceted
gems -- what's new in
designer cabochons and gem carvings --
gem of the month --
gem of the month archive --
birthstone of the month --
key to all the codes used on the ACS
site -- definitions of
terms used on the ACS site
-- how to order
-- about ACS --
about the ACS cutters --
settings for these gems
--faceting information
-- purchase UltraTec
equipment
-- Mail to
bsmigel@cox.net