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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December,
1999
APATITE
Apatite, a stone seldom found in
jewelry stores and virtually unknown to the general public, is
beloved by collectors for its many different colors and forms. Only
with the recent availability of the neon blue-green variety from
Madagascar has its jewelry use increased. The color of the best
specimens of this type rivals the famed Paraiba tourmalines, but
alas, this gem lacks their toughness and hardness. At 5 on the Mohs
scale, apatite must be cut, set, and worn gently. Earrings, pendants,
pins and tie tacks are probably safe, but ring and bracelet use
should be limited to occasional wear pieces with protective settings.
Care for this stone is similar to that given opals, it is heat and
shock sensitive, so steamers and ultrasonics must be avoided.
Gems are available in yellows and
various shades of blues and greens, some of the blues show chatoyancy
and can be cut as cat's eyes. Main sources are Brazil, Canada, India,
Mozambique and Madagascar.
Value
In today's market, the neon blue green
stones are valued much more highly than green or yellow stones. The
rarest of all varieties, a rich purple from Maine, tops the list.
Degree of polish can vary on this soft stone due to skill levels of
individual cutters, giving well polished stones premium value. As
with most gems, saturation of color, size and clarity are the major
determiners of value.
Gemological Data:
Makeup: Calcium Phosphate
Luster: Vitreous
Hardness: 5
Crystal structure: Hexagonal
Fracture: vitreous to uneven
Cleavage: imperfect, two
directions
Density: 3.20
RI: 1.63 - 1.64
Birefringence: .003
Pleiochroism: depends on color, may be
strong to weak
Dispersion: .013
Stones Currently Available:
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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