Transcript Gemstones - Gilbert Public Schools

Gemstones
are minerals, when cut and polished
demonstrate:
Beauty, Rarity, Durability, Size
Beauty
• Translucent (see through)
• Even color throughout is most prized
• Market colors are blue, red, yellow, and
green
• Exception is a colorless
diamond, with “brilliance”
(can reflect many colors)
www.pbs.org/.../diamond/images/gp06emerald.jpg
Durability
• Related to hardness, ability to
resist scratching
• Level 7 on Moh’s Scale (quartz is a 7)
• Opal is a soft gem – a mineraloid
• Displays “fire” or variety of brilliant colors.
http://www.mineralminers.com/images/sapphire-blue/gems/sblg136.jpg
Rarity
• Uncommon, very few found
• Large, Unique color
• Very few impurities
287.42 carats and is
considered to be one of the
largest yellow diamonds in
the world. Yellow diamonds
are extremely rare
http://www.mineralminers.com/images/ruby/gems/rbyg111.jpg
.
Size (portability)
• The stone represents a high concentration of
value in a small object, permitting the
owner to transport great wealth with relative
ease.
• Often the choice for ellicit trade.
What to look for in a Gemstone:
Color
• The more pure and vivid the
color, the more valuable
• even and translucent
The Hope Diamond
Cut
The cut determines the brillance
Of the gemstone
Clarity- addition of other
color or rock fragments
The Logan Sapphire Brooch
423 carats
Carat – approx. 0.2 grams or
1/5 of a gram
530.20 carats The Star of Africa, a stunning pear
shaped diamond
Precious or Semiprecious?
Precious – a gem must have
all 4 of the following qualities:
•
•
•
•
•
Beauty
Durability
Size
Rarity
Examples: Diamonds, Rubies,
Sapphires, and Emeralds
• Pearls and Opals are sometimes
included though they are not
minerals
Semiprecious
• Has only one or two of the
characteristics of precious
stones
• Examples: Topaz, Garnet,
Peridot, Amethyst,
Classifications – most common
•
•
•
•
Diamond – family is diamond – all carbon
Ruby – family is corundum- Al2O3 with Fe
Sapphire – family is corundum- Al2O3 with Cr
Emeralds – family is beryl- B,Al,Si,O green blue
color, also aquamarine, jade
• Quartz – family is quartz – SiO4 with other
elements
• Opals, turquoise, lapis lazuli
• Organics – pearls, coral, amber
Is it REAL?
Natural
• Formed in
nature
• has flaws,
often a part
of their
beauty
• REAL
Synthetic
• Made in lab
• Composition
the same
• No (or very
few) flaws
(inclusion)
• Difficult to
identify(leave to
the professionals)
• REAL
Imitations
•Not same
Composition
•Only “looks”
the same
•Plastic or glass
usually
•NOT REAL
Diamonds
•
•
•
•
•
Found in kimberlite – type of volcanic rock
Extreme temperature and pressure
Largest selling gemstone – MARKETING
Anyone can own one, not very expensive
Mined mostly in sub-Saharan Africa and
Australia
• Cut in Europe and Israel
Diamond Costs
• Environmentally – many are not mined
using environmentally friendly methods or
with safety for the miners a consideration
• Politically – to fund para-military groups or
insurgents against govt.s
• Illicit trade – easy to smuggle – “blood
diamonds”
http://www.fotosearch.com/thumb/IMP/IMP182/1525R-80643.jpg