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What To Look For When Buying Colored Gems
09/06/10
Buying colored gems is not nearly so easy as when looking to buy a jewelery
diamond. There is no universally accepted grading standard for dealers to adhere
to and the frustrations that come from finding that one dealer's "nearly
flawless" looks like another dealer's "moderately included".
As if what you found in the clarity of the jewelery column were not confusing
enough, how do you translate "daffodil yellow" or "sky blue"
let alone "rich royal purple with hints of velvety blue"?
Oh, and forget about cut grades! There is no standard for cutting, nor can
there be. Each stone has its own refractive index, which determines how the
light will play throughout the stone. This means that angles that will create
an incredible looking tanzanite might create a lifeless looking amethyst.
The GIA in its efforts to at least give us some guidelines in colored stone
grading and classification has gone to great lengths to provide us with a workable
system that is at best a good beginning.
Althouh there may never be a totally accurate system for describing colored
gems. Even photography does not provide us with an accurate system to share
the beauty of some colored stones, as the chemicals in the stone cause light
to react unfavorably, creating an unattractive looking stone where there is
great beauty in real life.
A person could spend countless hours and hundreds of dollars with a photographer
trying to get a good picture on an incredible chrome tourmaline jewel. It's
magnificent rich green color might come out an unattractive brownish yellowish
reddish color on film because of the chrome in the stone.
There are some basic guidelines that you can use in your search, but realize
that even with all the certificates you want, the stone that is beautiful to
you is the stone you should buy.
Colored gems are devided into three categories by the GIA for purposes of clarity
grading. Type 1, type 2 and type 3.
The GIA Colored Stone Grading Workbook states the following:
* Type 1 Colored Stones (Often virtually inclusion-free)
Click here to see chart 1
* Type 2 Colored Stones (Usually Included)
Click here to see chart 2
* Type 3 Colored Stones (Almost always included)
Click here to see chart 3
As you can see, a type 1 colored stone VVS grade is eye clean with inclusions
that are difficult to see under 10x magnification and invisible to the unaided
eye, while a type III VVS has inclusions that are easy to see under 10x magnification
and may have eye visible inclusions.
Complicated enough?
Understanding the above scales can be tough enough... try learning which stones
fall into which category. Don't be surprised if your local retailer does't know
each stone in every category... some won't even know as much as you do!
If your local jeweler does not have at least a fair understanding of which
stones should be normally eye clean, and which stones are still beautiful even
with fair amounts of eye visible inclusions, you may want to consider buying
colored stones from Jewelry.
Color is a specialists game! Everyone knows diamonds. They are the lifeblood
of our industry, but only a relatively few know and understand colored gemstones.
Be sure you are working with one of the few if you want the best value for your
money!
Now more about color:
To, quote from the GIA workbook on Colored Gemstones.
"Color is an interplay between a light source, an object, and the human
eye and brain. Most light sources emit light that is a combination (or blend)
of various wavelengths of visible electromagnetic radiation. The object absorbs
some wavelengths and transmits or reflects others to the eye. Receptors in the
eye translate these wavelengths into an optical code which the optic nerve transmits
to the brain, where they are interpreted as sensations of different colors."
Translation. Light hits the object that we are looking at and is absorbed or
reflected and we see it as different colors.
This is important!
Some stones will look completely different depending on whether they are seen
in fluorescent light or incandescent light. ALWAYS look at a stone you are thinking
of buying in several light situations. Get your jeweler to walk with you into
a room with fluorescent lights, incandescent lights and if possible out of doors
in shade and direct sun.
Back to "the book"
"We describe color in terms of three dimensions - hue, tone, and saturation.
These create a world of colors or color space. All colors perceived by the human
eye can be placed within this world, and their position specified by their hue,
tone, and saturation.
The color that is most prominent in a gemstone is called the dominant color.
Other evident colors are called additional colors."
To paraphrase hue is the basic impression of color that we notice immediately.
Red, green, blue are some of the basic hue names. Add in other descriptors and
you get a better picture. For example, lets take the color wheel from the short
journey between blue and green. Start with Blue, then shift slightly to very
slightly greenish blue, and on around the wheel to greenish blue, very strongly
greenish blue, green-blue or blue-green, very strongly bluish green, very slightly
bluish green, and finally ending at green.
You can take a similar journey from green to yellow, yellow to orange, orange
to red, red to purple and finally from purple to blue, which is why we call
it a color wheel. The human eye can actually discern about 150 separate hues,
but in gemology we use 31 on our hue chart which serves for the vast majority
of stones that you will see in the jewelry world.
Tone is the lightness or darkness of a color sensation, from colorless to black.
Tone is divided into eleven "steps from 0" being colorless through
ever increasing shades of gray to "10" being black. In grading colored
stones, we use seven of those steps, from "2 very light" through "8
very dark". The terms describe the lightness or darkness of the color the
eye perceives.
"Saturation is the strength, purity, or intensity of the hue present in
a color sensation."
What we attempt to describe with saturation is how bright or how dull the color
is. For example, with a blue stone here are terms we might use as we go up the
scale from color less to faint to strong, there are actually seven grades of
saturation starting with Neutral, but for practical purposes we will use six
modifiers for saturation.
Grayish blue, slightly grayish blue, very slightly grayish blue, moderately
strong blue, strong blue, vivid blue.
Blue is considered a cool color and cool colors are typically modified in shades
of gray. Warm colors such as orange will be typically modified in shades of
brown.
When you put it all together, you might get a color description of a really
beautiful sapphire such as this…
This sapphire has a medium dark, strong, violetish blue. Or if you are into
scientific color notation, vB 6/5. (violetish blue, medium dark, strong)
Wow! Does this sound like more than you need to know about a stone?
It more than likely is.
A person could enroll in the same courses jewelry expert must take and practice
for years, yet frequently two accomplished pairs of eyes will not see the same
color.
Then there is the issue of CUT! Cut right, the stone will SING! Cut poorly,
it is just another window, perhaps with a little sparkle around the edges.
So may we make a suggestion?
LOOK!
Don't wait. Get out there and look at LOTS of stones, then look some more.
You'll see that the vast majority of what is being shown to you is garbage.
Ask to see some well cut stones of high quality. Be prepared to go to several
stores until you find one that can show you the goods! You can save time by
starting at some of your better retailers (and by skipping the mall chain stores).
As a final note, look & see what can be done with stones that are NOT "native
cut". (Native cut is how we refer to stones that have been cut in the country
of origin with the purpose of retaining weight rather than releasing the beauty
of the stone.) Here is an example of a typical native cut stone versus what
it looked like after recutting. Which would YOU prefer?
For the most part. Take all of the above scientific "stuff" and enjoy
reading it and know a little of it, then throw it all out and VOTE WITH YOUR
EYES!
Colored gems are about BEAUTY! Buy the stone that makes your heart sing! If
you can't find one that makes your heart sing, spend you money on something
else!
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