The name 'Opal' is derived from the Greek word Opallios; the Latin Opalus whose origin is the Sanskrit Upala and they all mean the same 'precious stone'.

Opal is of a hydrous silicon dioxide chemical composition. It is amorphous which means it has no crystalline structure. Therefore, it is not a mineral but is known as a mineraloid.

Opal comes in all the colors of the rainbow like an abstract painting of luminous colors with a dazzling display of play-of-color.

In 75 AD, the Roman scholar Pliny marvelled that this "kaleidoscopic gem encompassed the red of ruby, the green of emerald, the yellow of topaz, the blue of sapphire, and the purple of amethyst".

Opal has a hardness ranging from 5.5 to 6.5 on the Mohs scale. This makes opal about the same hardness as glass which renders it easily cracked and chipped. It is transparent to opaque with a waxy to resinous luster.

Note: Opals have an incredible play-of-color displays but they do not change color like the color-change Alexandrite or Sapphires. Opals display Opalescence which means that color changes as Opal is viewed from different angles but not under different light sources. Alexandrite, on the other hand, change color under different light sources. Opalescence, therefore, is the alluring “play-of-color” exhibited by Opals. Bright reds, silvery blue, neon greens all dancing and leaping as you turn and move this precious stone. This brilliant display of colors is simply astounding.

The 'play-of-color' of Opals is the result of the millions of tiny spheres of hard silica in the gemstone. When light hits these spheres, it then bounces off at different directions and angles creating this unique play-of-color that make Opals highly esteemed and valuable.

Opals are in the list of precious stones that have captured the attention of humanity since pre-history; the others being emeralds, pearls, sapphires and rubies.

Opals are made up of tiny spheres silica and oxygen in chemical composition with some specimens having as much as 20% amount of water. This moisture can evaporate if the Opal is left under harsh and dry conditions, which will leave the Opal with a fine network of cracks which is called crazing. This crazing in Opals can only be fixed with treatment.

Opals come in two varieties: Precious Opals and Common Opals. Precious Opal is extremely rare; about 95% of all Opal mined from the opal fields are common or potch, a basically single colored rock of no real value.

Here I will be dealing with the Precious Opals that exhibits the play-of-color and are highly sought after.

Precious Opals are further divided into 3 main categories: White Opals which are the most common of Precious Opals; Black Opals which come with a dark background; and Fire Opals which are usually bright yellow, orange or red in color.

White Opal has a white, bluish, brownish, greenish fluorescence; whereas Fire Opal has a greenish to brown fluorescence.

The background color of Precious Opals is the product of impurities within the silica chemical composition of Opals.

Red Opal is the rarest and most highly priced and sought after. This is because Red Opal comes with larger spheres in its silica gel and this gives its red vibrant color. But this is not the most expensive of the Precious Opal. It is the Red Opal with the common black background that fetches a premium price.

The second rarest and sought after is the Orange Opal.

Opals also come with their unique patterns. The patterns seen in opals may resemble stained glass windows, colorful butterflies wings, colorful birds, and other rainbow-like natural mosaic forms.

One of the loveliest patterns is called the Harlequin in Opals. This pattern has a mosaic like appearance and it looks like a magnificent abstract painting of duplicating rounded, angular, or roughly square patches of about equal size. Harlequin patterned Opals are extremely rare and coveted.

The more notable patterned Opals are the Flagstone, Straw, Chinese Writing, Pinfire, Floral and Broad Flash Pattern.

There are so many patterns in Opals, not to mention varieties, and I will only concentrate on the most magical types of Opal that have magical healing properties and were known since pre-history.

The first which is the rarest and most valuable is the Black Opal. It is said that the Black Opal is possibly 130 times rarer than diamond. Black refers to the general background color which is not completely black but of a dark base color. This provides an excellent contrast to the vibrant hues. This precious stone is found in Australia and Ethiopia.

Next is the White or Light Opal which is the most common variety of Precious Opal. These milky and sometimes transparent Opal displays a gorgeous play-of-color.

Fire Opal is the next most known variety of Precious Opal. It is the yellow, orange or red variety. The Fire Opal that displays the play-of-color is known as Precious Fire Opal or Jelly Opal and is extremely rare. Mexico is the source of most Fire Opals.

Boulder Opal comes in different colors. However, what makes this Opal special is that it comes attached to its host rock. This host rock plays a part in making Boulder Opals so stunningly beautiful as the shimmering and glowing color of the Opal is perfectly set on this dark rocky background.

Matrix Opal displays specks and swirls of flashing colors which are the flecks of opals ingrained in the little pores in sandstone or ironstone.

Other branded opals include Koroit Opals, Yowah Nuts, Dendritic Opals, Opalized Wood Opals and Hyalite Opals. Opals are also named after the country where they were found such as Peruvian Opals, Tanzanian Opals and so on; also, of their unique color: Pink Opal, Blue Opal.

Composite Opals are natural Opals attached to a backing material such as black potch, ironstone or vitrolite to simulate black opal in what is called a doublet. Opals can also be made into triplets, that is to say, with a darker base and a protective crystal dome.

Now to the magical varieties of Opals. These include:

The Burning of Troy Opal: this is one of the most mysterious gemstones in history. In addition to that, it is one of the most elusive black opals. It earned its name due to the display of red color. It is thought to be reminiscent of a fire, glistening through the night. At the height of Napoleon Bonaparte’s power, it was a gift to his love, the Empress Josephine.

The Flame Queen Opal is perhaps the most famous of all opals. It is the best-known example of “eye-of-opal”, an eye-like effect created when opal in-fills a cavity. The center of the Flame Queen Opal gives the impression that it is on fire, but only the green frame encloses it. But the magic lies in its play-of-color which is chameleon-like, so bewildering and so beautifully alive. This is the Opal that brings the most luck and good fortune of all the Opals.

Cacholong, also known as Kalmuck Agate, is a variety of the common opal which is of a milky white colour and was used for carving, and cameos. The Cacholong Opal is a stone of true friendship, sincerity, and honesty.

Floating Opal is a small glass housing (usually an orb or teardrop) in which small chips of genuine opal float in liquid. If the opals do not move, it is NOT a floating opal. Many man-made opals (also known as Mosaic, Captured, and Frozen opals) are erroneously called floating opals. This precious stone was the beloved of many lovers, for it was this precious stone that was used to make sacred promises that must be kept. The Lovers would put the floating opal on a vessel of water as they join hands and pledge their friendship and love with utmost care and religiosity. Curses and misfortune would befall the faithless should such sacred promise be broken.

The Mexican Fire Opal also known as Girasol Opal is a beautiful specimen that displays hyacinth and yellow colors.

It is named for its brilliant red to orange body color which is partly due to iron oxide. Mined in Mexico, this Opal is lighter weight than other Opals. These Mexican Fire Opals tend to have one body color and do not usually contain the flashes of light and color typical of other opals. Mexican Fire Opal is the only natural opal that is normally faceted. Light and Dark Mexican Fire Opal varies from bright orange to reddish orange and is brilliant cut with precise calibration.

The Mexican Fire Opal was known and used as a sacred gemstone by the natives of Mesoamerica since ancient times.

Hyalite is a form of opal with a glassy and clear appearance which may exhibit an internal play of colors if natural inclusions are present. It is also called Muller's Glass, Water Opal and Jalite. The name Müller's glass is derived from the name of its discoverer, Franz-Joseph Müller von Reichenstein.

Hydrophane means water loving and this type of opal can absorb water rapidly. The first indication that an opal is hydrophane is the feeling of stickiness when touched. It was known in the United States as Magic Stone.

Menilite is a greyish-brown form of the mineraloid opal. It is also known as liver opal due to its color. It is called menilite because it was first described from Ménilmontant (Paris), France, where it occurs as concretions within bituminous Early Oligocene Menilite Shales. Menilite Opal was made into amulets for curing problems and sickness of the livers.

Brecciated Opal Jasper is form of Brecciated Jasper in which the cementing material is Opal. Opal Jasper is a jasper-like of resinous luster, dark red, Opal variety, known as the Opal of beautiful wisdom.

Pink Opal is a natural, pink colored gem-variety of the Common Opal which is composed of Opal, Palygorskite and Chalcedony. It was also known as Rose Opal. Pink Opal symbolized baby Cupid, and was called the Opal of Childhood.

Opalized Petrified Wood or Wood Opal is a form of petrified wood which has developed an opalescent sheen or, more rarely, where the wood has been completely replaced by opal. It was used as a charm to help trees grow healthy and strong.

Tabasheer is a hard, whitish, translucent substance extracted from the joints of bamboo. Consisting chiefly of pure silica, this opal-like herbaceous gem is highly valued in the East for medicinal purposes, and has long been considered a love potion of almost mythical powers.

In Mali, there was the belief that if you wore this as an amulet, that steel would do nothing to you. Tabasheer were known as Stones of Invulnerability and were highly esteemed by the Malaysians and Hindus alike. It was an Eye Stone, a remover of guilt, fears, and anxieties.

Opalized Fossils include vegetation or wood from the boulder opal fields and opalized clam shells from Coober Pedy. Opalized fossils also include sea shells, teeth, and even Opalized belemnites (squid). Opalized fossils are extremely rare and hard to find.

Opalized Fossils represent the eternal change that is manifested in nature. Change is constant and nothing remains the same.

It was said that all the colors of all the precious gemstones and gems are present in this one stone and it possessed all the virtues of the gemstones whose colors reside within it.

Poets and highly spiritual people in general have been praising and writing about the magical colors in Opal since ancient times.

For example, it has been written that the play-of-color in Opal have the power to cheer the heart, and to make the person holding the opal rejoice in life.

The ancient Egyptians and Babylonians used opal as a powerful protection against diseases; and named it the “Gem of the Gods”.

The famous anthropologist Louis Leakey discovered that people were making jewelry from Precious Opal thousands of years before the pyramids of Egypt were built.

They called Opal the Child Beautiful as Love, or the Cupid-Paederos. They also called it the Orphan or ORPHANUS, because it alone was all glorious, with no father and no mother to be equaled to.

It was believed that Opal came from heaven, and thus the Greeks gave it the name of KER-AUNIUS; and the Romans called it CERAUNIUM.

The early Greeks believed the opal bestowed powers of foresight and prophecy upon its owner.

Opal was used as a protective amulet against evil forces, as well as a protection against lightning strikes, and against the terrors that comes with the night.

In the Middle-Ages, Opal was called OPTHALMIOS, the Eye Stone. This was because OPHTHALMIS LAPIS was famous as an eye healer more so than the emerald and other gemstones that had the healing properties to cure eye problems. It helps soothe the eyes and nerves.

Opal was also known as Patronus Furum (the Patron of Thieves) because supposedly it bestowed the gift of invisibility.

Opal protected the wearer from malignant diseases such as cholera and sickness of the kidneys.

It was recommended that you place Opal between the eyes for clarity of thoughts; also, to hold an opal with your left hand and gaze upon it for manifestation of your desires.

During the Black Death in 1348 in Venice, Italy, it was noticed that Opals worn by people who were stricken with the plague became more brilliant and the luster of the Opal suddenly disappeared at the death of the wearer. People at that time started dreading this precious gemstone especially one worn by a victim.

In Sir Walter Scott's novel, 'Anne of Geuerstein', written in 1829, a young maiden died soon after a drop of holy water fell onto her opal talisman. This gave Opal a bad reputation for decades as a bad luck stone.

Opals have been found on Mars. As Opal is a hydrated silicate of which water is required for its formation, this discovery is significant as it proves that water once existed on the planet.

Shakespeare famously described the opal as the "queen of gems" and "a miracle". Opal brings vigor, power and stability in one’s love life and marital relationship.

Opal engagement rings especially of Boulder variety are increasingly popular due to its rarity and vibrant dance of rainbow colors.

Opal symbolizes the loveliness of the heavenly light which is the Sun. It exudes beauty and elegance and captivate hearts that have beholden it.

Opal deposits can be found in Mexico, Brazil, Honduras, the United States, Ethiopia, and Australia. 90 to 95% of all the opals in the world are mined in Australia.