A few facts and myths
about that beautiful opal you have locked away in your jewel case. Firstly,
it is a closely paled array of miliona of spherical particles of amorphous silica
stacked in a three dimensional grating. Because of the special grating of the
spheres, it is the only gemstone known to man that has the unique natural ability
to diffract - that is to split white light or ordinary sunlight into all the
beautiful colors of the rainbow.
Impurities play no
part in creating the colors of the opal as is the case with many other gemstones.
Color is created when light is split by voids that have been formed between
the spheres. The size of the voids are critical to the angle at which the light
is split hence the color produced. To produce color visible to our eyes, the
spheres that form the voids must be no smaller than 1500 angstroms for the violet,
indigo and blue colors, nor larger than 3500 angstroms for the orange and red.
When viewing a lovely
opal the most critical factor is the relationship of the light source to your
eyes. To see it at its sparkling best the light must be coming over your shoulder.
If you are in a room using natural light always stand with your back to the
window and if outdoors, stand with your back to the sun. Reverse these positions
and you will be amazed at the change of quality and color. The same principle
applies to most other forms of gems, hence the critical angel of light in the
Good stable Australian
opal has proved to be a sound investment over the past 25 years. It is one of
the few gemstones that has continued to appreciate in value at a steady rate.
This cannot be said for many other types of gems.
Australia has some
96% of the world's supply of commercial grade opal and suffers little of the
problems that seem to apply to many forms of opal from other countries. This
is due to the fact that it has been laid down under very special sedimentary
Gem opal is also
somewhat of an enigma. True, it is the birthstone of October, but it is a little
known and often misunderstood gem. Most jewelers have only a general knowledge
of it which is understandable. After all, more than 90% of their gem business
is diamonds and gold. The general public knows even less. They see the occasional
white-based stone with a hint of color in a jewelry store and think that is
it. It isn't! those are examples of the poorer quality, less colorful opals.
Instead think of a vibrant red macaw flying through a rich green forest. It
flashes bright red, blue and green colors as it weaves and bobs its way through
the trees. Bright flashing colors that change as the stone moves are what a
good opal is all about.
gemstone can be fraught with uncertainty. How do you know if it is a good
gem? whom can you trust? How much should you pay? The answer is knowledge.
Knowledge of what makes an opal beautiful, and knowledge of how this beauty
translates into market value will allow you to buy with confidence.
||This is not an
easy process. Judgment is required at every step and judgment is best honed
by exposure to opal. As you gain knowledge the task of valuing opal will