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Pleochroism may be important when
choosing the orientation in which the gem is cut, because this will affect the color
determining the hardness.
measuring the specic gravity.
determining the carat weight
Lecture 5: Crystallography
I. Internal Arrangement: It's what's inside that
Crystallography is a science about crystals. All minerals (and therefore most
gemstones) are crystalline and have a unique crystal structure. They are composed
of an orderl
Lecture 4: Color in Gemstones
I. What is Color
For some gems, color is the most important factor in determining value. Certain gemstones
have nearly immutable color, while others vary so endlessly the reasons behind their coloration
remain a mystery. To u
Lecture 3: Physical Properties of Gemstones
I. Hardness: Mohs' useful scale
Hardness is determined by a mineral's resistance to scratching. There are two
measures of hardness: scratch hardness and indentation hardness. Generally, we
use the scratch hardne
SELF TEST 4
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Match the following gem groups with one of their specific gem varieties.
1. Cat's Eye
Gems Lecture 2
Chemistry and Geology
Chemistry: the atom
-atomos means indivisible in ancient Greek (a=not, tomos=divided)
-concept of atoms and elements are closely linked
-an element cannot be broken down into simple
Gems Lecture 1
Intro to Gems
What is a gem?
-part of human history for over 20,000 years
-many early gems were made from organic materials (e.g. mother of pearl, bone)
-crystalline gems were likely rst gathered in