Color
Jewelers describe the color of a gemstone in terms of three
characteristics: hue, saturation, and tone. A gemstone's basic color is its
hue, and those with purer hues (for emeralds, green; for sapphires, blue; and
for rubies, red) are generally considered more valuable. Often, however, a hint
of another color can be detected. Sapphires will range from purplish blue to
greenish blue; emeralds, yellowish green to bluish green; and rubies, orangey
red to purplish red. Saturation is a measure of the intensity or purity of a
gem's hue and is determined by the degree to which gray or brown hues mute its
defining color. Value tends to increase with saturation, so a fully saturated
purplish blue sapphire may well be more expensive than a muted pure blue one.
The tone of a gemstone, a measurement of its lightness or darkness, is usually
given as light, medium-light, medium, medium-dark, or dark.
Clarity
A flawless gemstone is rare and usually extravagantly priced. As
with diamonds, most gemstones have inclusions, or tiny mineral flaws, that can
be seen under magnification or by the careful eye. Sapphires tend to be
moderately included, while emeralds and rubies are usually heavily to
moderately included. Make sure that any inclusions in the stone do not
penetrate deeply into the gem, as this may cause it to break or crack. Clarity
grades range from VVS (very, very slightly included) to I3, in which inclusions
are prominent and severely affect the gemstone's beauty.
Cut
A gemstone's cut refers to its proportions and symmetry. It is
essential in making a gemstone look appealing--the stone should be symmetrical
in all dimensions so that it will appear balanced, and so that its facets will
reflect light evenly, providing good brilliance. Color should also be taken
into account when cutting for optical efficiency. If a stone's color is highly
saturated, a shallow cut will allow it to pass more light, while a deeper cut
may increase the vividness of a less saturated gem. There is no generally
accepted grading system for gemstone cut.
Size
Though a gemstone's weight is usually given in carats, this may
not give an accurate idea of its size, because different types of stone have
different densities. Therefore, a 1-carat sapphire or ruby will be smaller than
a 1-carat emerald, though they have the same weight, because sapphires and
rubies (both a form of the mineral corundum) are more dense than emeralds.
Illustration of gemstone
dimensions
Gemstones can also be measured in dimensions
(diameter, length, and width). It is important to know the dimensions to ensure
that the gemstone weight will be visible and well proportioned in the
setting.
Treatment
Gemstones are often treated to enhance color and fill cracks.
Please note that, if a gemstone has been treated, this information will be
provided in the specifications on the stone's product detail page. There are
various accepted techniques, depending on the type of stone. For example, oils
and resins are frequently used to fill surface-reaching fissures in emeralds
and rubies. This process is not permanent, however; if a treated ruby or
emerald is subjected to high heat from a jeweler's torch, an ultrasonic or
steam cleaner, or even hot dishwater, the filler may leak out of the stone.
Sapphires and rubies are often heated in a kiln or furnace to enhance their
color. Such heat treatment, which is considered permanent, has been used for
centuries. Lightly colored sapphires may also undergo diffusion treatment. This
is done by heating a stone in the presence of coloring elements such as
titanium or iron, which causes a thin layer of color to be diffused into the
stone's surface. Because this color layer is so thin, a diffusion-treated
sapphire should not be repolished.
Care
To clean gemstone jewelry, first wipe it with a soft cloth to
remove any dirt. Emeralds require only the use of a soft cloth, as cleaners may
damage these soft gems. Sapphires and rubies can be cleaned with either an
ultrasonic cleaner or a solution of one part ammonia to six parts water, with a
soft brush. Store your gemstone jewelry in a soft cloth pouch or jewelry case
so it does not touch other pieces in your collection. As with all jewelry,
normal wear and tear can loosen prongs and settings, so it is a good idea to
have it checked by a professional jeweler who can make repairs as needed.
Color
Jewelers describe the color of a gemstone in terms of three
characteristics: hue, saturation, and tone. A gemstone's basic color is its
hue, and those with purer hues (for emeralds, green; for sapphires, blue; and
for rubies, red) are generally considered more valuable. Often, however, a hint
of another color can be detected. Sapphires will range from purplish blue to
greenish blue; emeralds, yellowish green to bluish green; and rubies, orangey
red to purplish red. Saturation is a measure of the intensity or purity of a
gem's hue and is determined by the degree to which gray or brown hues mute its
defining color. Value tends to increase with saturation, so a fully saturated
purplish blue sapphire may well be more expensive than a muted pure blue one.
The tone of a gemstone, a measurement of its lightness or darkness, is usually
given as light, medium-light, medium, medium-dark, or dark.
Clarity
A flawless gemstone is rare and usually extravagantly priced. As
with diamonds, most gemstones have inclusions, or tiny mineral flaws, that can
be seen under magnification or by the careful eye. Sapphires tend to be
moderately included, while emeralds and rubies are usually heavily to
moderately included. Make sure that any inclusions in the stone do not
penetrate deeply into the gem, as this may cause it to break or crack. Clarity
grades range from VVS (very, very slightly included) to I3, in which inclusions
are prominent and severely affect the gemstone's beauty.
Cut
A gemstone's cut refers to its proportions and symmetry. It is
essential in making a gemstone look appealing--the stone should be symmetrical
in all dimensions so that it will appear balanced, and so that its facets will
reflect light evenly, providing good brilliance. Color should also be taken
into account when cutting for optical efficiency. If a stone's color is highly
saturated, a shallow cut will allow it to pass more light, while a deeper cut
may increase the vividness of a less saturated gem. There is no generally
accepted grading system for gemstone cut.
Size
Though a gemstone's weight is usually given in carats, this may
not give an accurate idea of its size, because different types of stone have
different densities. Therefore, a 1-carat sapphire or ruby will be smaller than
a 1-carat emerald, though they have the same weight, because sapphires and
rubies (both a form of the mineral corundum) are more dense than emeralds.
Illustration of gemstone
dimensions
Gemstones can also be measured in dimensions
(diameter, length, and width). It is important to know the dimensions to ensure
that the gemstone weight will be visible and well proportioned in the
setting.
Treatment
Gemstones are often treated to enhance color and fill cracks.
Please note that, if a gemstone has been treated, this information will be
provided in the specifications on the stone's product detail page. There are
various accepted techniques, depending on the type of stone. For example, oils
and resins are frequently used to fill surface-reaching fissures in emeralds
and rubies. This process is not permanent, however; if a treated ruby or
emerald is subjected to high heat from a jeweler's torch, an ultrasonic or
steam cleaner, or even hot dishwater, the filler may leak out of the stone.
Sapphires and rubies are often heated in a kiln or furnace to enhance their
color. Such heat treatment, which is considered permanent, has been used for
centuries. Lightly colored sapphires may also undergo diffusion treatment. This
is done by heating a stone in the presence of coloring elements such as
titanium or iron, which causes a thin layer of color to be diffused into the
stone's surface. Because this color layer is so thin, a diffusion-treated
sapphire should not be repolished.
Care
To clean gemstone jewelry, first wipe it with a soft cloth to
remove any dirt. Emeralds require only the use of a soft cloth, as cleaners may
damage these soft gems. Sapphires and rubies can be cleaned with either an
ultrasonic cleaner or a solution of one part ammonia to six parts water, with a
soft brush. Store your gemstone jewelry in a soft cloth pouch or jewelry case
so it does not touch other pieces in your collection. As with all jewelry,
normal wear and tear can loosen prongs and settings, so it is a good idea to
have it checked by a professional jeweler who can make repairs as needed.
