|What is Lapis Lazuli?|
natural, isometric, 1 inch
crystal of lazurite (lapis lazuli) from near Badakshan, Afghanistan
Scanned photograph taken from The Gem
Kingdom by Paul E. Desautels, Random House, Inc. New York.
Lapis lazuli gets its brilliant blue color from its sulfur content.
The more evenly the color is distributed throughout the stone, the higher
the quality, and the greater the value. Lapis generally occurs with
a speckled and strained consistency, with glittering inclusions of iron
pyrite. If the pyrite is well distributed, the stones beauty
may be enhanced adding to its genuineness.
photograph taken from
Gemstones of the World,
Schumann (1997), p. 173.
Too much pyrite however may cause the stone to have a dull greenish
tint. The most costly and precious form of lapis lazuli is mined
in Afghanistan, having a rich uniform deep blue color, and little
to no white calcite veining (which may diminish the value), as well as
only a few flecks of glittering pyrite. Lesser quality
lapis lazuli is mined in Chile (Chile lapis) and also in Russia.
Lapis mined from these areas generally has a strong whitish or gray color
thus diminishing its value. Some smaller deposits of the stone have
been found in Argentina, Burma, Canada, and the United States as
well (Schumann, 1997, p. 173)
|Lapis Lazuli chemical composition|
|Index of refraction||approximately 1.5|
|Specific Gravity||generally 2.7 to 2.9, higher with increasing pyrite content|
|Hardness||5.0 to 5.5|
|Color||deep blue, purplish blue, or greenish blue|
|Table information taken from http://www.mineralminers.com/html/lapminfo.htm|
stone is often imitated by adding dyes to a variety of other stones or
synthetic materials. The dying process may also be used in combination
with the crushing of a less valuable grade of lapis lazuli and then reconstituting
it back together. The presence of iron pyrite deposits within a lapis
lazuli specimen would indicate that is most likely authentic, and has not
Caring for lapis lazuli
lazuli is rather porous, it should never come in contact with chemicals
and solvents. The best way to clean the stone is with mild, warm,
soapy water. Lapis, having only the hardness of 5 to
5.5 should be protected from rubbing and scratching against harder
stones and surfaces, such as other jewelry within a jewelry box.