For thousands of years, ruby has been considered one of the world’s most valuable gems because of its magnificent color, silky shine and excellent hardness. In modern usage, it is classified as one of the four precious stones, along with diamond, emerald and sapphire.
Ruby is a red variety of corundum – one of the hardest minerals on Earth, ranking 9.0 on the Moh’s scale of hardness (the diamond tops the scale at 10). Quality rubies in large sizes achieve top prices, often surpassing diamonds.
All things considered, color is ruby's most important factor when it comes to determining value. The name comes from ruber, the Latin word for “red”, thus red must be ruby’s primary hue, although is may exhibit a range of secondary hues, including orange, purple, violet and pink. The most desirable color is called "pigeon’s blood" (a pure red with a hint of blue).
Famous rubies include the 138.7-carat Rosser Reeves Star Ruby, which can be viewed at the Smithsonian Institution in Washington, DC, and the De Long Star Ruby (100 carats) displayed in the American Museum of Natural History in New York.
Myanmar has been the main source of the finest rubies. Other significant deposits are found in Afghanistan, Pakistan and Vietnam. Rubies of varying quality are mined in other parts of the world, including Australia, India, Russia and the United States.
Ruby is the birthstone for people born in July and one of the zodiac gemstones assigned to Capricorn and Cancer.
Emerald (along with diamond, ruby and sapphire) is a green member of the elite quartet commonly referred to as precious stones.
It belongs to the beryl family, and has a good hardness of 7.5 on the Moh’s scale.
The name comes from the Greek word smaragdos, which means “green gemstone”, and the green color of emerald is indeed unparalleled in the gem world. Clarity is also important, but inclusions (internal flaws) are tolerated more than in any other gem; they are often considered part of its character and used to assure the stone’s authenticity.
Emeralds have been treasured for thousands of years, throughout the world – from Egyptian pharaohs, through ancient Romans and Turkish sultans to Incas and Aztecs. The holy Indian scriptures mention emeralds as the precious green gems that promise good luck and enhance well-being. In the 15th century, emerald’s beauty inspired gem cutters to develop the emerald cut – a rectangular or square with oblique corners – which has been also applied to other gemstones, including diamonds. One of the most spectacular emerald specimens is the legendary 217.8-carat Mogul Emerald. In 2001 it was auctioned by Christie's of London for 2.2 million dollars!
Today Colombia is the main source of the finest emeralds. Significant deposits are also found in Brazil and in several African countries, as well as in the Ural mountains of Russia, Afghanistan, Pakistan, India, Australia and the United States (North Carolina).
Emerald is the birthstone for people born in May and the zodiac gemstone assigned to Taurus and Cancer.
Sapphire is classified as one of the four precious gemstones – along with diamond, emerald and ruby. It is sometimes referred to as the blue sister of ruby, since both jewels are varieties of the mineral corundum and exhibit the same exceptional hardness of 9.0 on the Moh’s scale (diamond tops the scale with the hardness of 10).
While blue is the classic color of sapphire, the gemstone is found in a variety of colors. In blue sapphire, the intensity of the primary hue is the most important factor. Violet and purple – the most common secondary hues – can contribute to the overall beauty of the color. The 423-carat Logan Sapphire displayed in the Smithsonian Museum of Natural History is one of the largest faceted gem-quality blue sapphires in existence.
The prized Kashmir and Burmese sapphires have long been known for their deep, velvety blue color, but are rarely seen on the market. Today, Sri Lanka and Madagascar provide most of the fine blue sapphires. Other sources of include Australia, Tanzania, Thailand, Cambodia, and the USA (Montana).
Sapphire is the birthstone for people born in September and the zodiac gemstone for Taurus, Pisces, Virgo and Sagittarius.
Long ago, it was decided that all color varieties of the corundum-based gemstones – with the exception of red, reserved for ruby – should be referred to as sapphire. Pink, however, presented a dilemma, the International Colored Gemstone Association eventually passed a resolution that the light shades of red should be included in the ruby category, since it is too difficult to establish where red ends and pink begins. In practice, pink shades are now known either as pink ruby or pink sapphire and are among the most beautiful of the corundum family.
Garnets are a group of silicate minerals known since the Bronze Age. The gemstone varieties occur in shades of green, yellow, orange and red. Most likely, the name was coined by the ancient Greeks, who noticed the similarity between pomegranate seeds – or granatum – and the garnet crystals embedded in the matrix.
Garnet bracelets and brooches were especially fashionable in the 19th century, but in the recent years the stone has enjoyed increasing popularity, thanks to its relatively good hardness (7.0 to 7.5 on the Moh’s scale) and the beautiful red hues that make it an affordable alternative to rubies and pink tourmalines.
The majority of today's garnet supplies comes from Africa, but the stones are also found in Sri Lanka, Thailand, Brazil, India, Madagascar, Canada and the USA.
The garnet is the birthstone for January and a zodiac gemstone for Aquarius and Capricorn.
Citrine, a beautiful translucent yellow gemstone, is a member of the quartz family. It is sometimes referred to as golden, Madeira or Spanish topaz, although it has little in common with topaz – except for color. It has been a popular alternative to the much more expensive yellow sapphire or yellow diamond.
The name comes from the French word citron (lemon), because natural citrine occurs in shades of pale yellow to pale orange. The intensity of color determines the stone’s value – the darker the color, the higher the grade. It has a good hardness of 7.0 on the Moh’s scale.
Brazil is the main source of citrine, but deposits are also found in Madagascar, Spain, Uruguay, Scotland, USA and Russia.
Citrine, along with yellow topaz, is the traditional birthstone for the month of November.
Peridot is a form of the mineral olivine. It is one of the few gemstones that occur in only one color – olive green. It is not particularly hard, with the ranking of 6.5 to 7.0 on the Moh’s scale.
The name can be traced to the Greek word peridona (“to give richness”), but peridot was already known in Egypt as early as 2nd millennium B.C. Ancient Romans esteemed its radiant green shine, which does not change in artificial light, and nicknamed it “the emerald of the evening”. Peridot can still be seen in shrines of many medieval European churches, most notably the Cologne Cathedral in Germany.
Today, the most beautiful stones come from Kashmir, but deposits are also found in Myanmar , China, the USA, Africa and Australia.
Peridot is the birthstone of August and one of the zodiac gemstones for Libra.
More than almost any other gemstone, each opal is distinctly unique due to the broad range of naturally occurring colors enhanced by light reflection phenomenon known as opalescence.
Opals are classified as non-crystalline forms of the mineral silica; most are more than 60 million years old, dating back to the Cretaceous period. Due to low hardness (5.5 – 6.0 on the Moh’s scale) and the natural presence of water within the stone, opals are very delicate and require special care to ensure longevity.
They can be found in a variety of colors, including wwhite, gray, yellow, red, green and blue, brown and black. The gem’s most striking quality is its ability to refract and reflect specific wavelengths of light so that its colors are displayed differently, depending on the light and the viewing angle. Most opals are finished en cabochon, because their optical properties are best displayed on smoothly rounded surfaces.
Opal is the national gemstone of Australia, which produces most of the world's supply. It is also found in Brazil, Mexico, Honduras, Slovakia, Japan and USA (Nevada and Idaho).
Opal is the birthstone assigned to October and to the zodiac signs of Libra and Aquarius.
Aquamarine was named after its blue or greenish-blue color that resembles sea water. It is a popular gemstone with beautiful luster, and good hardness (7.5 to 8.0 on the Moh’s scale) makes is a great choice for frequently worn jewelry, such as rings.
It belongs to the beryl family, which also includes emerald. The highest quality aquamarine is transparent, and the more saturated the color, the higher the value.
According to old legends, aquamarine originated in the treasure chest of beautiful mermaids, and since the ancient times has been regarded as the sailors' lucky stone.
Today, the leading producer of aquamarine is Brazil, and the biggest stone ever mined, which topped the scale at over 110 kilograms, was found near the city of Marambaia. Aquamarine deposits are also found in other parts of the world, including Australia, Myanmar , China, India, Pakistan, several African countries, as well as the United States.
Aquamarine is the birthstone for people born in March and the zodiac gemstone stone for Scorpio.
Topaz is commonly known as a beautiful light blue stone. Usually less expensive than aquamarine, it is a popular choice for rings, bracelets, necklaces, and pendants.
Topaz belongs to the family of silicate minerals and is one of few gemstones that can grow into enormous crystals. It has a good hardness of 8.0 on the Moh’s scale. Pure topaz is colorless and transparent, but it is usually tinted by natural impurities, which give it yellow, gray, reddish or blue-brown hues.
Naturally occurring blue topaz is quite rare. More common colorless, gray or yellow stones are often heat treated and irradiated to produce a more desired darker blue color. In 1969, blue topaz was named the state gem of Texas to celebrate a small deposit of natural pale blue topaz that was found in the state.
Blue topaz is the birthstone for people born in December.
Amethyst is considered the most precious stone within the quartz group. Because of relatively good hardness of 7.0 on the Moh’s scale, it is suitable for use in different types of jewelry.
The primary colors of amethyst range from pinkish violet to a deep purple, and it may exhibit secondary red and blue hues. Ddeep colors are the most valuable – particularly rich purple with rose flashes. The fines amethysts, called "Deep Siberian" or "Deep Russian", have a primary purple hue with blue and red flashes.
The Greek word amethystos translates into "not drunken", and the ancient Greeks and Romans often used amethyst to make wine goblets, believing that it would prevent intoxication. Uuntil the 18th century, amethyst was regarded as a precious gemstone. Thanks to its purple color, it was often featured in royal insignia, and is said to be the favorite gemstone of Catherine the Great. It was also popular among the high ranks of the Catholic church and referred to as "the stone of bishops".
Amethyst is found in Brazil, India, Madagascar, Namibia, Russia, Sri Lanka, in locations across the USA, Canada and in other parts of the world.
It is the birthstone for people born in February and one of the zodiac gemstones for Aquarius and Pisces.
Color is the major characteristic of tourmaline. This stone is found in more hues and shades than almost any other gem, which makes nearly every tourmaline specimen unique. It is also one of the most complex of all gemstone minerals (a silicate compounded with aluminum, iron, magnesium, sodium, lithium, or potassium), which accounts for its extraordinary range of colors.
Pink tourmaline displays a wide array of shades – from reddish, rose, and salmon to hot saturated pink, including unusual bi-color and tri-color pieces. It is one of the few pink gems that can be found in large sizes – pink tourmalines over 5 carats are still quite affordable.
Tourmaline combines good hardness (7.0 to 7.5 on the Moh’s scale) with great durability. The finest gems have excellent transparency and vitreous luster.
One of the most unusual qualities of tourmaline is its electrical property – it can generate electric charge when heated or rubbed. Thanks to this phenomenon, tourmaline was once widely used to clean the ashes from pipes; it is still used today in piezoelectric sensors.
Tourmaline is found in many locations throughout the world, but it is one of the few gemstones for which the USA is famous – during the 1900's, Maine and California were the world's main sources of this stone. Today most of the tourmaline supply comes from Africa, Madagascar, Brazil, Australia, Sri Lanka and Russia.
Tourmaline is a birthstone for the month of October.
Tanzanite is a relatively new, blue-colored gemstone. It was discovered in the foothills of Mount Kilimanjaro in 1967, and since then has been mined exclusively in Tanzania.
Tanzanite has a hardness of 6.5 on the Moh’s scale. Its colors range from light violet-blue to ultramarine blue, and pure blue with hint of purple is the most desired shade. Tanzanite will often appear to have different colors (purple, or brownish yellow) depending on the viewing angle and lighting conditions.
It was first named "blue zoisite", after the silicate mineral that it’s composed of. Tiffany & Co., which first introduced the gemstone, thought that the original name sounded too much like "blue suicide" and wouldn’t sell well. Tanzanite was thus chosen as a more fitting option. One of the most famous examples of tanzanite is the 242-carat Queen of Kilimanjaro, set in a diamond- and garnet-accented tiara displayed at the Royal Ontario Museum in Toronto.
In 2002, Tanzanite was added as the official modern birthstone for December.
In the gemological world, the term onyx refers to layered gemstones, which commonly exhibit parallel bands of various colors, such as white, tan, brown or black.
Onyx is a form of chalcedony and belongs to the large quartz group. It has a smooth, waxy luster and the hardness between 6.0 and 7.0 on the Moh’s scale.
Black-and-white layered version has been nicknamed “zebra onyx”; brown and white onyx is known as sardonyx, and red and white is called carnelian onyx. Solid black is perhaps the most famous color, but the vast majority of black onyx available on the market has been artificially colored and polished to enhance appearance.
Onyx was used by early Egyptians to make fancy pottery items. It was also known in ancient Greece and Rome (the name comes from the Greek word for fingernail or claw). During the 1950s, onyx was very popular in men's signet rings. Today it is often seen in necklaces and small jewelry items, and used as a backdrop for cameos.
It is one of the zodiac gemstones for Leo.
Precious coral or red coral is the common name given to Corallium rubrum and several related species of living organisms that form tree-like colonies in the depths of warm seas. It has been harvested since antiquity to produce beautiful red jewelry.
It is worth noticing that coral and pearl, although different in appearance, are chemically very similar. Both are mostly calcium carbonate deposited by marine invertebrates.
Various shades of red are the most popular colors associated with this gemstone, but natural corals can occur in a variety of colors, including blue, white and black. The skeleton of red coral branches is naturally matte and porous, but can be polished to a glassy shine. Coral has a low hardness of only 3.5 on the Moh’s scale. Due to its softness and opacity, it is usually cut en cabochon or used to make beads.
Corals live at depths of between three and 300 meters in the Mediterranean (particularly off the coasts of Algeria and Tunisia). the Red Sea, the Bay of Biscay, around the Canary Islands, in the waters around Australia, Japan, Taiwan and the Malaysian Archipelago.
Blood coral is one of the zodiac gemstones assigned to Taurus.
Turquoise is an opaque, blue mineral that has been used as ornamental stone for thousands of years. Hardness (between 5.0 and 7.0 on the Moh’s scale) and richness of color are two major factors that determine the value of turquoise. The colors ranges from sky blue to greenish and yellowish gray. The most desirable turquoise is a strong "robin's egg" blue. Delicate veining, caused by impurities, is often welcomed and regarded as a proof of authenticity.
The name derives from an Old French word for "Turkish", because the mineral was first brought to the West from Turkey. Long before that, it was mined in the Sinai Peninsula and graced the necks of Egyptian pharaohs and other ancient nobles . Turquoise has been used by southwestern Native Americans to produce beads, carvings, and mosaics.
For thousands of years, the finest blue turquoise was found in Persia (Iran), and the term "Persian Turquoise" has become synonymous with high quality and is still used, regardless of the stone’s origin. Most of the turquoise mined today come from the United States, but they are also found in northern Africa, Australia, Siberia, and parts of Europe.
Turquoise is one of the zodiac gemstones of Sagittarius.
Lapis lazuli is a beautiful gem valued for its deep blue color. It has also made significant contributions to the art world as the traditional source of blue pigment used in paints.
Unlike most gemstones, lapis lazuli is not a mineral but an opaque rock, largely consisting of lazurite. Its colors range from grayish blue to deep indigo, with varying amounts of white and gold speckles caused by the presence of calcite and pyrite. With the hardness of 5.0 and 6.0 on the Moh’s scale, lapis lazuli is among the less hard gemstones.
Lapis Lazuli has been treasured since the days of ancient Mesopotamia, Egypt, Persia, Greece and Rome. In some Middle Eastern cultures, it was considered a holy stone and believed to have magical powers.
For centuries, ground lapis lazuli was the only source of the pigment called ultramarine, used to produce blue paint that can be seen in countless paintings dating back to pre-Renaissance times. The old formula is still used today in art restoration and conservation projects.
Afghanistan has been the primary source of lapis lazuli, and several 6000-years old mines are still in use today. Secondary deposits are found in the Chilean Andes, in Siberia (Russia) , Canada, the USA and other locations.
Lapis lazuli is one of the zodiac stones assigned to Libra.
Jade is an ancient gem most often associated with a mesmerizing deep green color and a mirror-like luster.
Since the 19th century, the term “jade” has been applied to two distinct but similar minerals – nephrite and jadeite. Jadeite is rarer and typically ranks higher on the gemstone market. It has a hardness of 6.5 to 7.0 on the Moh’s scale. In addition to various shades of green, jadeite comes in many other colors, including white, yellow, red, blue, and black.
The emerald-green “imperial jade” is traditionally the most highly valued variation. White or yellow color is preferred in China, where the stone has been treasured as the “royal gem” since 3000 B.C. Jade was also esteemed in early Western cultures – Mayas and Aztecs used to value it more highly than gold. Eventually, the name was coined by Spanish conquistadors, who called it piedra de ijada ("stone of the side"), because the gem was believed to cure kidney stones if rubbed against the body.
Currently, the best known sources of quality jadeite are the USA (California), Myanmar, New Zealand and Guatemala; other localities include Kazakhstan, Russia, British Columbia, Alaska and Italy.
Jade is one of the zodiac gemstones assigned to Virgo.