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.

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

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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:

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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