All about gold Pure gold is what we call 24 karat gold, and is a
bright yellow. It is also very, very soft- so soft in fact that it can
be scratched using your fingernail. It is also expensive- selling now at
a near high point of over $1000 US an ounce.
For the reasons
above gold is almost never used in jewelery in its pure form. Apart from
the bright yellow colour and the cost becoming astronomical very
quickly, the fact that it is so soft does not lend itself to jewelery
that will stand up to regular wear and tear.
Explaining karats
Pure
gold is melted and mixed or alloyed with other metals to help make it
stronger. The amount of the other metals changes the karat. Gold that is
equal parts pure gold and some other metal (a 50% blend) will be 12
karat gold- or 50% of 24 karat.
This is why different places have
different laws as to what can legally be sold as gold. In most of Europe
and Asia, you can old sell it as "gold" if it is more than 50% pure
gold- so more than 12 karat. This is why 14karat is the most common gold
available commercially in these places. It is hard enough to wear well,
and mixed with enough other metals to bring down the price
substantially. In North America is is common to find 10 karat gold which
has, in reality, less than 50% gold content.
A rainbow of colours- but no white
Changing
the type pf metal added to pure gold changes the colour of the metal.
Adding silver leads to green gold. Copper to red or pink gold, iron to
blue gold, and aluminum to purple gold. Each type of metal addition also
brings with it new challenges. For example the silver in green gold
leads to gold that can tarnish like silver. Purple gold is known to be
very brittle and is better treated as an accent stone rather than the
metal to hold a piece together.
Each type of gold changes colour
in much the same way you would mix paints. Yellow gold plus shiny copper
equals a reddish toned gold. You never actually remove the yellow
colour- you just hide some of it with other hues. This is why a true
white gold with that gleaming platinum-like finish does not truly exist.
"White" gold is mixed mostly with nickel, an inexpensive white metal
that helps to tone down that bright yellow colour. When mixed the result
is a lovely buttery grey that is beautiful in it's own right.
Commercial
white gold jewelery is often plated with rhodium to give it that
platinum like look that is currently so popular. Be aware that this
coating almost always wears off of high traffic areas of jewelery
leaving the grey yellow underneath it more visible. There are new white
gold mixtures being brought to market that use other alloying metals,
but they are not yet commonly available.
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