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Quality
And Value Of Gemstones
Knowledge is Power. So let's
start. Becoming an
educated consumer is not such an easy matter when dealing with all the variables related
to the purchase of a colored gemstone.
These
many variables will determine the quality,
therefore the price. In general, the
quality and value of a gemstone is determined by a combination of what are called the
""Four C's"": Clarity
(degree of flawlessness),
Color,
Cut and Carat
weight.
Clarity is the degree of flawlessness. As a
general rule, a clear transparent gemstones with no
visible flaws is the most valued.
GIA (Gemological Institute of America) classifies colored gems
clarity of three types:
Type 1 gemstones, "virtually inclusion-free" such as aquamarine, topaz,
green tourmaline, tanzanite, citrine, damburite.
Type 2 gemstones, "usually included" such as rubies, sapphires,
garnets, peridots, amethysts, zircons, cat's eye chrysoberyls, pearls, corals.
Type 3 gemstones, almost "always included", such as emeralds and red tourmalines.
Some gemstones are valued for their inclusions! Phenomenal gemstones owe their stars and
eyes to inclusions. Tiny inclusions reflecting back light put the eye in the
cat's eye and the star in the star sapphire.
Inclusions can also be a birthmark, telling us where a particular gemstone was mined.
Let's talk about sapphire clarity. Since it is a type2 gem, the sapphire is
generally a "usually included" gem. Look therefore for an eye clean gem. If the
inclusions are too numerous, visible to the naked eye and distracting, avoid
such stone. It is probably a low quality stone.
Color is another key factor. A common misperception in judging gems is
that people assume that the
darker the color, the better the stone. That isn't true: color can be too dark, like some
sapphires that look more black than blue. If a gem's color
is too dark, it is subdued and
 lifeless. A much better rule of thumb is the brighter and
more rich and vivid the color, the better. In
 general, within each gemstone variety, a
clear, medium-tone, very intense and saturated primary color is the most preferred. Muted
colors or colors between hues, which you might find very attractive, are usually less
expensive. Look at the color in different kinds of light. Sometimes, in daylight, a gem
shows one color and in artificial light another one. This color change gems are usually
very attractive and in most case expensive. (alexandrite is the most known example, but
sapphires, garnets, spinels can also change color).
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
(see the stone on the right). 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 so-called window...see the stone below, on the
left). The best way to judge cut is to look at similar gemstones next to
each other.
The weight of a gemstone is
measured in Carats and points. There are 100 points
in one carat, which equals to one-fifth of a gram. As a rule, the price increases per
carat as we go from smaller to larger stones, since the larger stones are more limited in
supply. However, the price does not increase proportionately - there are disproportionate
jumps. And the larger the stone (all else being equal in terms of overall quality), the
more disproportionate the increase in cost per carat may be.
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