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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JASPER
Jasper is an opaque, solid or patterned variety
of cryptocrystalline quartz (chalcedony) which consists of very tiny
(sub-microscopic) quartz crystals colored by various trace elements
or mineral inclusions. The names of jaspers can come from their
color(s): bloodstone, red, white, green; from their pattern:
orbicular, poppy, leopardskin, landscape, parrotwing; or from a place
name like Owyhee, Morrisonite, Mookaite, Madagascar, or Biggs. Many
times fanciful "trade" names are given to jaspers with unique
patterns which helps to "romance the stone". One case in point is a
particularly interestingly patterned piece of landscape jasper I cut
that I dubbed "Starry Night" due to its evocative resemblance to Van
Gogh's famous work.


[Place name japspers: Owyhee,
Biggs, Mookaite, Madagascar]




[Jaspers named for their
colors or pattern: bloodstone, parrot wing, poppy, dalmation jaspers
and "Starry Night" jaspers]
Jewelry use of jaspers goes back to the
early history of civilization and has been in and out of fashion many
times. Currently jaspers are "in" as are many opaque gems. The
strength of the cryptocrystalline structure makes jasper one of the
few materials other than jade that has successfully been used for
single piece (hololith) jewelry pieces. The variety of patterns and
solid colors make it a favorite of intarsia and inlay artists as
well.



[Antique watch fob featuring
green jasper and carnelian, antique stick pin with bloodstone and
diamond, contemporary "plum blossom" jasper hololith bangle bracelet,
intarsia featuring landscape jasper in center plaque]
When slow mineral replacement of organic
remains results in an opaque, silicated replica of the original
structure, then such pieces would properly be called "petrified". One
of the most popular fossil jaspers is petrified dinosaur bone.


[Jaspers of petrified:
dinosaur bone, palmwood and pine cone]
All types of jasper take an
excellent polish, are trouble free to care for, and hardy enough for
all jewelry uses, although at hardness 7,
daily wear rings will need an occasional repolishing. Stones are
usually cabbed, sometimes carved, and rarely faceted. Various forms
of this material are also frequently made into decorative objects,
such as ashtrays or bookends. Jaspers are found all over the world,
with certain colors or patterns unique to particular locales. Most
bloodstone comes from India, all Mookaite from Australia. Although
there may be rare exceptions, the vast majority of jasper on the
market is unenhanced and synthetics are not available, so any piece
you see, can reasonably be presumed to be both unenhanced, and of
natural origin.


[Carved, matte finish red
jasper pair, contemporary dalmation jasper/pearl necklace, abstractg
carved "willow" jasper piece]
Value:
Most jaspers are common; hence much of the
value in a piece relates to the saturation of its color, the beauty
of its pattern or the artistry with which it is fashioned. Some types
such as Imperial jasper do command premium prices, though, for their
relative rarity. As in the case of agates, the many named varieties,
modest price and dramatic patterns make this gem an ideal
"collectable" for both beginners and those whose collections are more
mature.

[Premium prices would be given
for this piece of rare green Imperial jasper, and for this
particularly notable landscape jasper specimen]
Gemological Data:
Makeup: Silicon Dioxide
Crystal Structure: Trigonal
Hardness: 7
Luster: Vitreous
Density: 2.61
RI: 1.53-1.54
DR: 0.004
Cleavage: none
Stones Currently Available:
{Search
our Catalog}
Go to: Homepage
-- what's new at ACS --
monthly specials and
discounts -- "buried
treasures" -- BWS/FS jewelry
designs -- gem topic of the
month -- gem topic
archive -- birthstones
-- ask Barbara --
key to all the codes used on the ACS
site -- definitions of
terms used on the ACS site
-- how to order
-- about ACS --
setting these gems
-- free gemology course
-- Mail to
barbara@acstones.com