Precious Stones

Agate

Agate is formed in concentric layers that lends itself to a multi-colored striped appearance. It is a translucent to opaque stone varying from milky white to red or yellow-brown. This ensures that no two agates are quite the same. It is often used in cameos and other fashion jewelry and is usually cut as a cabochon.

Alexandrite

Natural alexandrite is an extremely rare gem. This gemstone has the ability to change its color from green to red depending on the light source as well as versions of purple and blue. It appears green in normal daylight and changes to a red to purplish-red in incandescent light. Alexandrite is a very unique and beautiful gemstone.

Amethyst

Amethyst is part of the quartz mineral family. Still, its deep and attractive color makes it extremely popular. Amethyst is a transparent gem, lilac to deep purple in color. The deeper the color, the more valuable it is. The most common enhancements are heat and irradiation. Try not to expose an amethyst to excessive amounts of bright sunlight, as this can fade its color.

Amethyst is the birthstone for February.

Aquamarine

Aquamarine is a transparent sea blue gemstone. Its color ranges from very light watery blue to medium dark blue with greenish tones. The deeper the color and the better the clarity, the more valuable the gem is. Fairly large and clear aquamarines with good color are among the more valuable semi-precious gems. They are often given step cuts, also known as "emerald" cuts, much like aquamarine's mineral sister, emerald. Good clarity is important in these stones, especially lighter ones where flaws will be more visible. Brazil is the primary source of aquamarine, although it is mined in other places as well.

Aquamarine is the birthstone for March.

Blue Topaz

Topaz is a hard, brilliant, transparent stone with a wide range of color options. The "pure" topaz color is yellow and was often confused with chrysolite, the yellow variety of peridot. However, the use of distinct colors has helped topaz come into its own.

There are two variations of this mineral group - precious and imperial. Blue topaz is an example of a precious topaz. Imperial topaz is more rare and consequently more valuable.

Blue topaz in particular is popular in jewelry today. It has a watery blue color similar to aquamarine but often without the green overtones, and its hardness and good clarity make it an excellent gem. The blue color is often enhanced through heat-treatment and irradiation.

Blue topaz is the birthstone for December.

Citrine

Citrine is a member of the quartz family that ranges in color from light yellow to a very deep root beer (Madeira) color. Because of its abundance, there are plenty of fairly large, clear stones available for jewelry. Clarity and a rich yellow color are keys to look for in a citrine. It has some of the same characteristics as amethyst, such as alternating bands of lighter and darker color, but these bands are harder to see in citrine.

Citrine is the birthstone for November.

Crystal

Crystal is a mineral that represents a diamond. It is a white, colorless gem that is a diamond look-alike with good durability and brilliant sparkle. Even though they occur in nature, all crystals that are sold as jewelry are lab-created. Crystal is created using a combination of silica (quartz sand) and natural minerals. To avoid stress and inclusions, the glass is cooled slowly.

Emerald

Emerald is part of the beryl mineral family and one of the most valuable gems on the market. The brilliant green of a fine emerald is unmatched by any other stone, and the extreme rarity of top-quality emeralds make them fairly costly.

Almost all emeralds have inclusions in them, called "jardines". The fewer of these impurities, the more rare and more costly the stone is. Because of these inclusions, emeralds can be brittle, so protect your emeralds from hard contact when you wear them. Ultrasonic cleaners, which use vibrations to remove dirt and buildup, can be dangerous to heavily included emeralds. Natural emeralds also tend to have thin scratches on the surface. A layer of wax or oil is usually applied to smooth out their appearance and enhance their color. This layer may have to be replaced professionally every few years.

Emerald is the birthstone of May.

Garnet

While garnet is often viewed as a ruby substitute, it has its own unique qualities that can be appreciated. Garnet comes in a variety of colors, including many shades of red (from very pale to brick to a red-black), but it is never blue. It usually has good clarity, comes in larger sizes and has a respectable hardness that allows it to wear well.

Garnet is the birthstone of January.

Iolite

The name "iolite" comes from the Greek "ios", which means violet. Iolite is sometimes known as "water sapphire" because of its light violet blue color, but other iolite gemstones may range from clear to honey yellow.

The ability of iolite to exhibit different colors depending on how it is cut is what led Viking explorers to use it for navigation as a polarizing lens to look directly at the sun.

Jade

Jade is a translucent to opaque stone, which varies in color from pale to rich in color. This gem has been known as the "royal gem" in China for 5000 years, and it was once valued more than gold by the Mayans and Aztecs.

Jade is divided in two groups: Jadeite and Nephrite. Nephrite is the more common of the two and may range in color from dark green to grey-green. In some instances it can also be white, reddish or yellowish. Jadeite, which is rarer, is usually green but also includes white, pink, red, violet, black and brown hues. It's normal for jade to contain streaks and other blemishes. These are not necessarily considered flaws. In fact, some of the patterns created are considered to add value to a piece.

Lapis

Lapis lazuli or commonly known as lapis, is a rock made of a combination of minerals. This stone is known for a vivid opaque blue marble color with hints of gold tone (pyrite). This stone may be dyed to darken the blue hue. Lapis can include the following minerals: lazurite, calcite, pyrite, sodalite, augite, diopside, enstatite, mica, hauynite, hornblende, and nosean.

Lemon Quartz

Lemon quartz is a very sunny and bright stone. It is very fashionable and coordinates well with pastel colors and stones such as blue topaz and peridot.

Since most quartz has been heated to enhance its color, the stones should be kept away from prolonged exposure to strong light or heat.

Mother of Pearl

Mother of pearl is the iridescent internal layer of mollusk shells and is composed of the same material as pearls. Though technically not a gemstone, mother of pearl is used in all types of jewelry from mother of pearl watch faces to mother of pearl fashion jewelry.

Mystic Fire

Mystic fire topaz is a colorless topaz that is enhanced with a patented Azotic Coating producing a permanent and stable blue-green appearance with a rainbow of color accents. The Mystic fire topaz is similar to the rainbow topaz but is enhanced in a completely different manner. Mystic fire topaz is not found in nature.

Onyx

Onyx is part of the chalcedony family of colored quartz, which includes agate, cornelian and jasper. It is usually seen in black but it can come in other colors. Sardonyx is onyx that is red to brownish in color.

The striking black and crisp lines of onyx makes it especially popular for jewelry. Because the lines can form in many different ways, each piece of onyx has a unique appearance. Onyx is also popular for cameos - when an image is carved into onyx, the color of the next band shows through. Onyx is opaque (meaning no light shines through it), therefore, it is usually cut into a smooth, rounded, polished dome called a cabochon.

Opal

Opal is made of the same ingredients as quartz, except it contains a little water and has not been compressed into crystals. As a result, it is softer than quartz and has to be treated a little more carefully to avoid damage. The shifting colors seen in opal, called "fire", are the result of microscopic spherical structures within the stone that reflect different wavelengths of light depending on their spacing, creating the colorful shimmering effect. There is no other gemstone that looks remotely like it. It comes in both black and white varieties, with black being the most rare.

Opal ranges from transparent to opaque. Its value is based on the "play of color" with red being preferred as the dominant color. Cabochon cut is the preferred shape to enhance the play of color. A black background with color play is the more valuable black opal. Boulder opal is a stone that has veins of opal running through the host rock (iron matrix).

Opal is October's birthstone.

Peridot

Its color is its most important quality and can range from yellow green to a striking chartreuse color. (The chrysolite name, in fact, often refers to peridot that is more yellow than green.) The stones have good clarity and are appropriate for faceted cuts since light sparkles through them. They are relatively soft and should be protected from abuse.

Peridot is the birthstone of August.

Rhodolite

Derived from the Greek words "rhodon" and "lithos" meaning "rose stone", rhodolite is a type of garnet that varies in color from red-violet to a rich pink-red.

Ruby

Along with the emerald and sapphire, ruby is one of the most prized colored gems available. The main quality of the ruby is its bright red color. The most valuable color is a dark true red without pink or purplish tones. The deeper the color, the more valuable it is. The best color usually comes from Burma and is very costly. Stones from Thailand are darker but clearer and much more common. Only red stones are called rubies. If the color is too light to be called red, it is a pink sapphire.

Ruby is the red variety of corundum. Corundum, the main material of ruby, is the second-hardest material known after diamond. In gem quality, rubies over 2 carats can be more costly than a diamond.

Inclusions and flaws are fairly common, and many rubies are treated to enhance their color. In general, one should look for a bright red stone with as few inclusions as possible. Synthetic rubies offer good color, clarity and size and are more affordable.

Ruby is July's birthstone.

Sapphire

Sapphire is another variety of corundum. Sapphire differs from ruby in color only. Any color other than red that occurs in the corundum mineral will be a sapphire. The most common color in sapphire is blue. The most desirable and valuable blue shade is the "corn flower" medium blue and transparent. If a sapphire occurs in other colors than blue, the term "fancy" must be used to describe the color.

Sapphire often has some inclusions, but clarity is still quite good. Its base material, corundum, is the second hardest in existence and, therefore, wears very well. Often, the sapphires used in jewelry are heat-treated or given chemical diffusion to enhance their color. These enhancements are permanent. Like rubies and emeralds, there are good synthetics available for people who like the color but not the cost.

Sapphire is the birthstone of September.

Tanzanite

Tanzanite is a type of zoisite and wasn't found until 1967, when a deposit was uncovered in Tanzania. This is still the only source for tanzanite and one of the most recent additions to the gem world. It gained almost immediate popularity both for its scarcity and its rich, blue-violet color. Tanzanite is often heat-treated to bring out a uniform color. Caution should be used when it is worn in rings, since it is fairly soft and can be scratched or chipped. Although it usually has good clarity, tanzanite can be damaged by ultrasonic cleaners, so other cleaning methods are recommended.

As a birthstone, tanzanite can be used for the month of December in place of blue topaz and turquoise.

Tiger's Eye

Tiger's eye is an opaque stone that can be yellow to brown. It features a narrow gleam of light down the center that appears to move vertically along its surface as the light sources move. The unique appearance of tiger's eye is caused by fibrous inclusions. Light is refracted off of these inclusions giving tiger's eye its chatoyancy (changeable luster). Hawk's Eye is similar to Tiger's Eye but instead has a gray blue or green hue due to the presence of crocidolite when the stone was created.

Topaz

Topaz is a hard, brilliant, transparent stone with a wide range of color options. There are two varieties - precious and imperial. An example of precious topaz would be blue topaz. Imperial topaz is more rare and consequently more valuable.

Topaz, and especially blue topaz, has grown in popularity over the years. The "pure" topaz color is yellow and was often confused with chrysolite, the yellow variety of peridot. However, the use of distinct colors has helped topaz come into its own. Blue topaz in particular is popular in jewelry today. It is watery blue like aquamarine, but often without the green overtones. Its hardness and good clarity make it an excellent gem. The blue color is often enhanced through heat-treatment and irradiation.

Blue topaz is December's birthstone, and yellow topaz is used as November's birthstone.

Tourmaline

Known as the "Rainbow Gemstone", tourmaline comes in every color of the rainbow, and most tourmaline gemstones are multi-colored. The most common color is forest green. This mineral often has many color variations within the same crystal creating bi-color and multi-color specimens. Red with green is the most common bi-color. When the crystal forms with the red inside surrounded by green, it is called "watermelon". Deep red tourmaline is called "rubelite".

Gem cutters focus on bringing out the deepest color when cutting tourmaline. Still, when viewed from different angles, a tourmaline may exhibit several different colors.

Turquoise

Turquoise is an opaque stone that has been popular for centuries. Colors range from an expensive "robin's egg" blue to the less valuable green. Turquoise can darken with age and turn greenish. The best quality turquoise is "robin's egg" blue with even color throughout.