How to buy a gemstone
Here In Gemstone Buyin
g Guide
we are trying to tell you about gemstone quality. After finishing our gemstone
buying advice, you will know more than the average jeweler. But you have to go through
ALL our gemstone buying advice: gemstones are much more complicated than diamonds (which is why most jewelers don’t
know much about them). So concentrate! Gemstones have no grading system, each variety
has individual value factors, and within each gem variety, quality
dramatically affects price: a ruby can be worth $10 or $1,000,000.
Everybody agrees what the best stone is, that’s easy. But the best buy?
That’s tricky. Hold on, we’ll take you there! First, the basics. Like diamonds,
gemstone quality and value are evaluated according to the "four Cs":
color, clarity, cut, and carat weight. For ruby, sapphire, and to a lesser
extent emerald, country or origin also affects value. Unfortunately,
colored gemstones are also commonly treated, so that also affects value
for ruby, sapphire and emerald in particular. Let’s start with the most
important gemstone value factors, color, clarity, and carat weight.
Judging
Color
Color is the important factor. But its not true
that the darker the color, the better the stone. Atleast not correct every time: color
can be too dark, like some sapphires that look more black than blue. Think
grass green, not forest green. Fire engine red, not burgundy. The more
bright and vivid the color, the better.
In precise grading terms: clear,
medium-tone, intense and saturated primary colors are the most preferred.
Pure blue, not greenish blue. Pure red, not purplish red. Muted colors and
colors between hues, which you might find very attractive, are usually
less expensive. Look at the color in different kinds of light.
Judging
Clarity
The next most 
important factor affecting
value is clarity: clear transparent gemstones with no visible flaws are
the most valued. There is no standardized grading system for clarity:
it varies by gem variety. With colored gemstones, if the inclusion doesn’t
show in the face up position, it generally doesn’t matter at all. (unlike
diamonds which are graded upside-down at 10x magnification). Some
varieties, notably emerald and red tourmaline, are very rare without
inclusions of some kind so the price structure takes this into account.
Pastel colored gemstones show inclusions more, so they generally detract
more from the value for pale stones.
In rare cases, inclusions can increase
value. Special effects like the star in star sapphire and the eye in
cat’s-eye chrysoberyl are caused by inclusions. Inclusions can also be a
birthmark, proving that a gemstone is from a particular place. So
"horse-tail" inclusions in demantoid garnet make it more valuable because
they prove it came from Russia. But more about origin later.
Carat Weight
and Prices
Gemstones are sold by weight, not by size.
Prices are calculated per carat, which is one-fifth of a gram. Some gems
are denser than others so the same weight stone may be a different size!
For example a one-carat emerald is a bigger than a one-carat ruby. Just
like diamonds, the carat weight also affects the price: large gemstones
are more rare, so the price per carat is higher. But practically, this
doesn’t make much of a difference with common gems like amethyst, citrine
and blue topaz. It really kicks in for ruby, emerald, sapphire,
and demantoid garnet,tourmaline, spinel, and pink topaz.
Another
important quality factor, which makes a big difference in a gem’s beauty,
but may not add much to the price is cut…
Judging
Cut
A good cut is something that may not
cost more but can add or subtract a lot of beauty. A well-cut faceted
gemstone reflects light back evenly across its surface area when held face
up. If the stone is too deep and narrow, areas will be dark. If it is too
shallow and wide, parts of the stone will be washed out and lifeless. The
best way to judge cut is to look at similar gemstones next to each other.
Look at these three stones.
See the dark areas in the stone on the left and right? These are caused by
light leaking out the back of the stones because the angles aren’t right.
Look for a stone like the one in the middle which has even
brilliance. Colored gemstones
come in lots of different cut variations, many more than diamonds. Choose
whichever cut style appeals to you: just make sure that the angles are
right and light is coming back to the eye in a pleasing way.In addition to choosing different gem cuts,
try different varieties. Even in red, blue, and green, there are lots of
gem alternatives.
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