Name: _____________________________
Nonfiction Reading Test
Diamonds
Directions: Read the following passage and answer the questions that follow. Refer to the text
to check your answers when appropriate.
Diamond is the hardest material on Earth.
Yet, gem cutters shape them. If diamonds
are so hard, how do they cut them into
shape? They use other diamonds of course!
Not all diamonds are the same. Some are
harder than others. The hardness of a
diamond depends on two things: its purity
and its structure. Let's discuss purity first.
Diamonds come in many colors: grey,
white, yellow, blue, pink, purple, orange
and black. Red diamonds are the rarest of
all. This makes them worth a lot of money.
Yet, pure diamonds are colorless. They are
all carbon. They are transparent like glass.
Colors found in diamonds come from
impurities. They have another element
besides carbon. They have a carbon defect.
For example, yellow diamonds have
nitrogen in them. The nitrogen is yellow.
Blue diamonds have boron trapped in their
crystal structure. The boron is blue.
The purity or color of a diamond is
important to its hardness. Pure diamonds
are harder than impure diamonds. But
purity isn't the only thing that matters.
Structure also affects hardness.
The carbon atoms in a diamond are
arranged in a crystal structure. Some
crystal structures are perfect. A diamond
with a perfect crystal structure is harder
than one with flaws. So pure, colorless
crystal diamonds are the hardest of all.
Good gemstones should be hard. This is
what makes diamonds so great for jewelry.
Some gems, such as azurite, are soft and
easy to scratch. Azurite looks pretty, but it
will scratch if worn daily. Diamonds do not
scratch easily. Only a diamond can scratch
another diamond.
That's why you can wear a diamond ring
while doing chores, if you want. The gem
will not need polishing. Just don't go fist
bumping other people with fancy
engagement rings. It will end badly.
