. The word precious has evidently
two meanings - and both being adjectives - can definitely confuse even to the
most knowledgeable person. The funny thing about it, is that some varieties of
these precious stones may be as pretty, and even more expensive than a precious
stone. The value of these specimens is a function of their purity, quality, color,
perfection of its crystals, size, durability (thanks to their hardness), and so
forth. So don't be surprised next time you see an opal from Coober Pedy
Australia in or around thousands of dollars.
In summary, these are the only four precious
stones in the world, everything else even though look precious, are
semiprecious stones. Of course, for the mineralogist, and experience rock
collector, there are also semi-ugly and very ugly stones (good to practice
pitching). What makes them gain such qualification is the opposite of the
adjectives of a precious stone. Following are the only four precious stones in
the world:
Diamond (multi color, sapphire (blue), emerald
(green) and ruby (pink to red). Following is the description of each and every
one.
Diamond.
Chemical Formula: C
Composition: Carbon 100.00%
Molecular Weight = 12.01 gm
Environment: Gas rich, ultra-basic diatremes
from mantle depths (>30 km), and alluvial placer deposits derived from the
Kimberlite (in honor of Kimberley, South Africa) rocks. Kimberlite consists of
olivine, garnet, pyroxene, and calcite.
Localities: Kimberly, republic of South Africa.
India. Brazil. Ural Mountains, Russia. Murfreesboro, Arkansas, USA.
Name Origin: From the Greek, adamas, meaning
"invincible" or "hardest."
Sapphire.
Chemical Formula:
Al2O3
Composition: Aluminum
52.93% and Oxygen 47.07%
Empirical Formula:
(Al2O3)
Environment: Contact and regionally
metamorphosed rocks.
Locality: Tchainit and Yakutia, Russia.
Name Origin: Probably derived from the Sanskrit,
kuruvinda, meaning "ruby."
Synonym: Leucosapphire - colorless (I do not
agree, but that is what you find in the Dana classification). If it does not
have the beautiful blue color, it's just plain and simple: is everything, but a
sapphire!