is a form of quartz, with the characteristic pale lilac to deep purple
resulting from small amount of iron or manganese impurities in the crystal.
The darker specimens mined in Africa and Australia are generally considered
the more desirable. Lighter colored amethyst may also be heat treated
to form citrine.
The relatively low cost and beautiful color make amethyst a perennial
favorite for jewelry. Amethyst is manufactured in a wide range of calibrated
[standardized] sizes and shapes.
Amethyst can fade after prolonged exposure to sunlight, so it should
be stored accordingly. Your stone may be cleaned with warm, soapy water,
jewelry cleaning solution, or an ultrasonic cleaner.
Aquamarine is a blue to blue-green variety of the beryl. Unlike emerald,
the green form of beryl, emerald, aquamarine gems are often completely
flawless. Aquamarine occurs in relatively large masses, with some specimens
weighing in the thousands of carats.
The darker the blue color the more valued the specimen, and stones with
a greenish tinge are generally less expensive. Most aquamarine sold
today is heat treated to improve the blue color.
Since aquamarine is so widely available, synthetic material is cost-prohibitive
to produce and is not found on the market. Synthetic blue spinel is
sometimes sold as aquamarine. Blue topaz is also difficult to distinguish
from aquamarine. Both materials are less valuable than real aquamarine,
so this gem should be purchased from a reputable dealer.
Aquamarine can fade after prolonged exposure to sunlight and your stone
should be stored accordingly. Aquamarine should be cleaned with warm,
soapy water or a jewelry cleaning solution. Do not use an ultrasonic
Citrine is a form of quartz with a yellow to gold to orange brown hue.
Citrine is mined naturally, but most is created by heat-treating amethyst.
Heat treated citrine will have a slight reddish tint not found in entirely
natural specimens. The availability of citrine means that it is quite
affordable and manufactured in a broad range of calibrated [standardized]
shapes and sizes.
Because of its color citrine resembles topaz, and has sometimes been
sold under misleading names such as gold topaz, Madeira topaz, Brazilian
Topaz, citrine topaz, or topaz quartz. Citrine and Topaz are entirely
different substances, so buyers should beware of such titles.
Like amethyst, citrine will fade after prolonged exposure to sunlight.
Your stone may be cleaned using lukewarm soapy water, a jewelry cleaning
solution, or an ultrasonic cleaner.
Emerald is the green form of the mineral beryl. The most important factor
in choosing an emerald is the color. As a general rule, the more vivid
the green, the more valuable the stone.
Emerald is notorious for inclusions, called "jardins," and
flawless stones are extremely rare. This is such a common trait that
some buyers are suspicious of stones without inclusions since they are
considered more likely to be synthetic. Because inclusions are expected,
they do not detract from value to the same degree as with other stones,
unless they are so deep as to weaken the stone.
Inclusions are traditionally filled with oil to mask their appearance,
although newer methods have also been developed. Stones which have been
treated with oil should never be immersed in hot or soapy water or cleaning
solutions, and should never be subjected to ultrasonic cleaning. In
each case the oils can be removed from the treated stone, thus damaging
its appearance. Emeralds may also develop internal cracks if struck
or subjected to sudden temperature changes.
Garnets are not a single type of gemstone, but a group of mineral forms
with similar chemical and physical properties. While garnets are commonly
thought of as red, they occur in a almost every color except blue. "Color
changing" garnets which have a differing appearance depending on
the light source are also mined.
Six types of garnet are used as gems: pyrope; almandine, spessartine,
grossular, andradite; and uvarovite. Garnets are generally hard, durable
gemstones which can be cleaned using all common methods. An exception
is the rare demantoid [an andradite form], which should be cared for
more gently since it is less hard than the other types.
Opal is a multi-colored gem prized for the iridescent color flashes
it displays when viewed from different angles. These flashes of color,
known as "opalescence," determine the value of an opal. Opals
with demonstrate this "play of color" are referred to as precious
opals. Opals with little or no play of color are called common opals.
Black opal is the most valued of the precious opals. This form may have
a black, dark blue, brown, or very dark green background. White opals,
which range in color from white to cream to yellowish background, are
the next most treasured members of the family. A third common variety
is the fire opal. Fire opals have a transparent or translucent orange
to orange-red color.
Opals are unique among gemstones in that their brilliance results from
the presence of water molecules, rather than trace metals, within the
crystal structure. For this reason opals can be damaged by sudden changes
in temperature, or by prolonged exposure to strong light or high temperatures.
Do not clean an opal using ultrasonic cleaners or jewelry cleaning solutions,
as these can damage the stone. Opals should be cleaned in cool or warm,
soapy water and given a coat of light oil once or twice per year.
Peridot, the gem form of the mineral olivine, takes its characteristic
yellow-green to olive-green color from iron contained in the crystal
structure. Peridot is treasured as the goddess Pele's tears in Hawaiian
culture, and deposits of the mineral are often associated with volcanic
Peridot is a relatively soft gemstone and should be cleaned with care.
Use a soft brush and warm soapy water to clean your peridot, and do
not use ultrasonic cleaning.
The name ruby is reserved for red forms of corundum, the same mineral
called sapphire or fancy sapphire in other colors. Transparent, intensely
colored ruby has been among the most precious stones for centuries,
and top-quality rubies can still sell for more than comparably sized
A unique form of ruby displays a six-point star pattern, called asterism,
caused by light reflections from tiny rutile needles oriented along
the crystal faces. Twelve-point stars also occur infrequently. "Star
rubies" are often shaped into smooth cabochon cuts to best display
this effect. When viewed under a favorable light source the star seems
to move across the stone as the lighting angle changes.
Rubies should always be purchased from a reputable dealer. Rubies are
extremely difficult to distinguish from red peridots, and synthetic
rubies have been available since the early twentieth century.
Rubies and sapphires are very hard stones so they can withstand jewelry
cleaning solutions, ultrasonic cleaning, or washing with warm soapy
Sapphire is a variety of the mineral corundum. It can appear in almost
every color except red. [Actually, red corrundum does occur, but it
is called ruby rather than red sapphire.] The color blue is so commonly
associated with sapphire that stones of any other color are commonly
referred to as "fancy sapphires."
"Color changing sapphires" are an unusual form which takes
on a differenct appearance depending upon the light conditions. A color
changing sapphire may appear blue in under natural light conditions,
but take on a violet hue under artificial lights.
Sapphires are very hard stones so they can withstand jewelry cleaning
solutions, ultrasonic cleaning, or washing with warm soapy water.
Things You Should Know Before Buying a Sapphire :
The color of a sapphire is one of the strongest determinants of
its value. Blue sapphires come in a range of shades. The brightest,
most intense are the most valuable. Learn more about how color affects
the value of sapphire.
Clarity is the other most important factor in determining the value
of a sapphire. A high quality sapphire must be free from visible
inclusions (internal imperfections). Learn more about how clarity
affects the value of sapphire.
Large, quality sapphires are rare and expensive. For the
same color, clarity and cut, the larger the sapphire, the more valuable
it is. See pictures and learn more about how size affects the value
Most sapphires available in jewelry are quite poorly cut. Perfectly
cut sapphires are usually only available in the finest jewelry and
their price reflects a premium. Learn how to tell the difference
between a poor cut and a quality cut before buying your sapphire.
Read about how cut affects the value of sapphire.
Synthetics and Imitations: Sapphires are often synthesized
and imitated by other substances. In addition, almost all natural
sapphires undergo some kind of treatment process. Learn about these
before sapphire shopping. Read here to learn about treatments, synthetics
and imitations of sapphire and how to tell the difference.
and Symbology: Sapphire has been revered for centuries
all over the world. It is rich with symbolism and special healing
properties. Learn more about sapphire meaning and symbology to see
if it’s something you relate to.
Spinel, a magnesium aluminate mineral, occurs naturally, in almost any
color. The deep red varieties are among the most popular since they
are virtually indistinguishable from ruby. In fact, the 170-carat "Black
Prince's Ruby" in the British Imperial State Crown was determined
to be spinel, but only through sophisticated x-ray diffraction testing.
Since spinel is relatively easy to synthesize, you should purchase natural
stones, particularly clear stones, only from a reputable dealer. In
a strange twist, flawless natural spinel is now found less often than
ruby, although the latter remains more valuable.
Spinel occurs naturally in octahedral [eight-sided] crystals. Some of
these crystals are large enough that they can simply be polished and
mounted in jewelry settings without any other faceting. Spinel is a
durable stone and can be cleaned safely using common methods.
Topaz occurs in almost all, but the most valuable form is the golden
to yellow-orange form known as imperial topaz. Heat treated gems are
now widely available in blue and pink forms.
Use care in purchasing topaz, as unscrupulous dealers have developed
a long list of deceptive names for stones with a similar appearance.
Examples include: gold topaz, madeira topaz, brazilian topaz, bahia
topaz, citrine topaz, indian topaz, and smoky topaz. In short, be wary
of any descriptive term before the work topaz, other than "imperial."
Topaz nearly as hard as diamond, so it can withstand a great deal of
wear. Like diamond, however, it can also be split by an unfortunate
blow along the right crystal plane. Topaz can be cleaned with warm,
soapy water or jewelry cleaning solutions. Do not use ultrasonic cleaning.
Tourmaline is available in almost any color, and even occurs with two
or even three colors in the same specimen. Like garnet, tourmaline is
not a single mineral, but a group of minerals with similar chemical
and physical properties. A favorite form is watermelon tourmaline, with
the red center surrounded by a green "rind," or vice versa.
Because of its long, thin crystal structure tourmalines are commonly
shaped as long rectangular bars. Tourmaline is also "pleochroic,"
meaning that the color changes depending on the angle at which it is
viewed. The darkest color will always be seen as you look down the long
axis of the crystal.
Tourmaline is a hard and durable, and can be cleaned using common methods.
You should avoid exposing the stone to high temperatures.