Alexandrite, the color changing gem, was named after Tsar Alexander II following its discovery in the Ural Mountains of Russia in 1830. Symbolic of transitions, this gem changes from a vibrant emerald green in daylight to a luscious red when under incandescent light. The greens are often accompanied by hues of blue while its reds are often accompanied by purple. The color change of alexandrite is further effected by its nature as a pleochroic mineral. This means that its color change is also influenced by the angle from which it is viewed. Major resources for alexandrite include the Ural Mountains of Russia as well as parts of Brazil and Sri Lanka.
- Hardness: 8.5
- Mineral: Chrysoberyl
Amber, which is golden-brown in color, is fossilized tree resin which ranges anywhere from one million to hundreds of millions of years in age. It may contain insects, reptiles, and plant particles. These organic inclusions will vastly increase the value of the amber if they are well preserved. Elektron, which in Greek means product of the sun, is both the Greek name for amber and the origin of the English word electron. Amber in fact has triboelectric effects, meaning that it acquires or shares electrons upon contacting other specific materials. Amber is found in and anywhere near the Baltic Sea. It is also currently being recovered from the Dominican Republic and Mexico. Red and blue are the least common colors in which amber is found.
- Hardness: 2.5
- Mineral: Organic Plant Resin
From the Greek word amethystos, meaning not drunken, amethyst was esteemed by Greek and Roman cultures not only for its believed ability to guard against intoxication, but also for granting its possessor a sharp wit. Its hues vary from a pure, and valuable, purple to a pale violet that is sometimes accompanied by faint blue and green hues. Its primary source is Brazil and other South American countries. Until the discovery of these sources just a couple hundred years ago, amethyst was valued as highly as ruby, sapphire, and emerald. It is a variety of quartz which can also be found in yellow, golden, or orange; when found in these colors, it is known as citrine. Furthermore, amethyst and citrine may form in the same crystal, which is then known as ametrine. Quartz may also be green, which is named prasiolite.
- Hardness: 7
- Mineral: Quartz
A cousin to the emerald, this variety of beryl is identified by its light blue, transparent, water-like color. Named after the latin phrase for seawater, it has been said to keep sailors on their course and safe from danger. Sources of aquamarine include South America, Afghanistan, Pakistan, India, and the Ural Mountains of Russia. A dark blue variety of the gem is found in Madagascar. Like many gems on today's market, the aquamarine usually undergoes color treatments to achieve a more pure blue, while the untreated aquamarine often has a greenish tinge.
- Hardness: 7.5 to 8
- Mineral: Beryl
From ancient Rome, it was a symbol of the beauty and love of Venus. From the Maharajas of India, it was believed to bring luck and health. Emerald is the green variety of beryl, a cousin to aquamarine and morganite. Its green color comes from trace amounts of chromium and ultimately defines the value of the gem. Inclusions, defined as imperfections within a gem, are tolerated as they are nearly always present. This causes a certain fragility and unless it is set in a proper design, it is usually not recommended for everyday wear. Emerald can be found all around the world, but the primary sources for the gem are Columbia and Zambia.
- Hardness: 7.5
- Mineral: Beryl
Red garnet has historically been a favorite of nobleman and royalty alike; its color, a display of their power and class. Garnet is most commonly seen in the jewelry trade as a dark red gemstone. However, garnet forms in many varieties including green, orange, yellow, red, purple, brown, black, blue, and colorless. Each of these colors belongs to subcategories of a large mineral group of twenty species called the garnet group.
The garnet species pyrope is mother to the deep red variety that is most commonly seen in the jewelry trade. In the trade, the red variety of pyrope is referred to as the Mozambique garnet, after the place from which it is commonly mined. Two other well-adored varieties belong to the pyrope species: the rhodalite garnet and the blue color-changing garnet. Rhodalite, Greek for rose, is a pinkish-red color. Blue garnet is the rarest of any garnet variety. It appears a grayish-blue color on average but can change from a blueish-green in daylight to a blueish-purple in incandescent light. It was only recently discovered in the late 1990s in Madagascar, but has since been found in Maine, California, Colorado, Russia, Tanzania, Turkey, and Kenya.
Garnet is a large mineral group of twenty species. However, only six are considered major species and only three of these six are necessary for a basic education in jewelry trade. These three are grossular, adradite, and pyrope. These species have subcategories of their own but this paragraph will focus on the few that are primarily used in jewelry. The garnet species grossular is responsible for a common green variety known as tsavorite. Tsavorite, in its richest green, appears as a light emerald. It is found in Tanzania as well as the place from where its name is derived: Tsavo, Kenya. Adradite is the garnet species that is responsible for a slightly more valuable variety of green garnet called demantoid. Demantoid has been dubbed the Emerald of the Urals, after the mountains from which it is most commonly found, and its strong resemblance to fine emerald.
- Hardness: 6.5 to 7.5
- Mineral: Garnet
Morganite, the sister of emerald, is the pink variety of the beryl mineral family. It was discovered in 1910 in Madagascar and named after JP Morgan in honor of his donation to the Museum of Natural History. Morganite is a pleochroic gem, meaning it displays different colors depending on the angle from which it is viewed. Its color changes from a bluish pink to a purer, pale pink. Sources for morganite include Brazil, Mozambique, Afghanistan, and Madagascar.
- Hardness: 7.5 to 8
- Mineral: Beryl
When seasonal rains soak dried earth, they carry silica into underground rock. Upon drying, these silica deposits eventually develop into opal. The color of the opal is determined by the size of its silica spheres and the pattern in which the spheres are stacked. These factors influence how the opal diffracts light, and therefore, the colors and intensity of the colors that result. A common repute dubs opal an unlucky gem. However, this reputation is simply attributed to the 1829 novel by Sir Walter Scott titled Anne of Geierstein. Most of history rather respects opal as the luckiest of gemstones. This is because it displays the colors of many other prized gems and may symbolize the possession of an "all around character." Fine opal may contain the green of emerald, the red of ruby, the purple of amethyst, the blue of sapphire, and the yellow of topaz. Australia's Outback is, incomparably, the primary source for fine opal.
- Hardness: 5 to 6.5
- Mineral: Hydrated Silica
A fine pearl is a combination of many delicate attributes. It is the product of a mollusk, such as a mussel or an oyster, that begins as a simple irritant within the shell of the mollusk. The mollusk continuously rotates and secretes coats of nacre upon the invasive irritant until the irritation is subdued. The natural pigment of the nacre will decide the color of the pearl, while the shape of the pearl is mostly influenced by the shape of the initial irritant.
For trade, pearls are categorized as either natural or cultured. A natural pearl simply lacks human intervention, while a cultured pearl begins with the deliberate insertion of a tiny bead. The most successful method of culturing pearls was developed in 1893 by Kokichi Mikimoto. Today, many people falsely believe that the Mikimoto brand utilizes a superior method. However, nearly all cultured pearls are developed using the same process that was originally developed in 1893.
The Akoya cultured pearl and the Chinese freshwater pearl dominate the cultured pearl industry. The largest and most valuable type of cultured pearl is the South Sea pearl, a product of the large oyster Pinctada Maxima. This pearl is usually between eight and fifteen millimeters and is typically white, cream, pink, or gold. Also of great value, is the Tahitian pearl, commonly called the black pearl. It is rarely a pure black, but instead has overtones of green, blue, silver, or purple. Like the South Sea pearl, it is relatively large and cannot be mass-produced.
- Hardness: 2.5 to 3
- Mineral: Organic Mollusk Nacre
History has held the ruby as one of the most sought after and most valuable of gemstones. Even today, ruby can sell for the highest price per carat of any colored gem. It has been believed in numerous cultures to promote peace, safety, and even invincibility in war. Its deep reds riddle human emotion and stir the vitality of life's passions. Present cultures recognize ruby as a symbol of success in wealth, love, and life. The value of ruby is primarily determined by its color. The ideal shade of red is often described as pigeon blood red. Along with sapphire, ruby is a part of the mineral species corundum. Red corundum is ruby, while all other colors fall into a category of sapphire. Ruby owes its red to traces of chromium. Typically, the more chromium that is present in a ruby means that the ruby will have a purer red and a higher value. Sources for ruby include Burma, the Himalayas, Vietnam, Myanmar, and Tanzania.
- Hardness: 9
- Mineral: Corundum
The blue sapphire has been revered by cultures to bring sincerity, faithfulness, and nobility. Although many default to the color blue when "sapphire" is mentioned, it is not only blue. The term sapphire describes any color variety of the mineral corundum that is not red, being that red corundum is defined as ruby. Sapphire may be blue, yellow, pink, orange, green, purple, or colorless. It is especially rare in its orange variety, often accompanied by a pink hue, called padparadscha, which is Sinhalese for lotus flower. A trace amount of chromium is responsible for the pink and red varieties of corundum, while the presence of iron and titanium contribute to the more common blue sapphire. Asterism, a star-effect, may appear on the surface of a piece of properly cut cabochon corundum. The gem is then classified as a star sapphire if blue or star ruby if red. Major sapphire mines are found in Sri Lanka, Tanzania, Madagascar, Thailand, Myanmar, and Australia.
- Hardness: 9
- Mineral: Corundum
An overnight celebrity of the gemstone world, tanzanite was discovered in 1967 in the hills of Merelani, Tanzania. In 1968, the hills had over 90 claims for mining and the gem was featured by numerous famed designers. In quick time, tanzanite came to challenge the three historical masters of the gem-trade market: ruby, sapphire, and emerald. Merelani, Tanzania remains the only source for tanzanite. Its limited supply and high demand has granted it an ever increasing value since its discovery. But for now, this violet-blue beauty still sells for less than the other three precious gemstones. Tanzanite is pleochroic, meaning it displays different colors when viewed from different angles. Its colors range from blue to violet to purple. The blue-violet varieties will typically retrieve the highest price on the market.
- Hardness: 6 to 7
- Mineral: Zoisite
Topaz is a very common gem in the jewelry trade. Often thought of as only being blue, topaz forms naturally in many colors including brown, yellow, green, orange, red, purple, and pink. Blue is, in fact, one of the least commonly found in nature. Nearly all of the blue topaz in the jewelry trade is color treated via irradiating colorless topaz at a specific electron voltage. Generally, topaz is categorized as a semi-precious gem, but there are two varieties that are much more valuable. These varieties fall into a category known as precious topaz, and include imperial topaz and sherry topaz. Imperial topaz displays a combination of red and orange, while sherry topaz displays some combination of yellow, brown, and orange. Topaz is not shy about its size, with the largest mined crystal weighing 596 pounds. Although it is mined in numerous countries, the world's major sources for it include Russia's Ural Mountains and Brazil.
- Hardness: 8
- Mineral: Topaz
Due to its wide array of vivid colors and the fact that is was usually mistaken as a different gem, there is very little history on tourmaline. Tourmaline is a mixture of boron, silicon, and aluminum, with the addition of another element that defines its color. For example, iron is present in green and blue tourmaline while manganese is present in the pink and red tourmaline. Some of the more popular colors have earned special names in the gem trade. The green tourmaline is called chrome tourmaline when its green is intense enough to resemble that of an emerald. Watermelon tourmaline is a mix of pink and green. A very valuable form is the ruby red variety, this tourmaline is referred to as rubellite. Varieties of tourmaline can be mined on every continent.
- Hardness: 7 to 7.5
- Mineral: Tourmaline