Definition
Mohs scale hardness 5.5 to 6.5
The most colorful gem is the opal. Its exquisite color play is unmatched, and good specimens can possibly be more expensive than diamonds. Iridescent color flashes make up the stone's color play, which varies depending on the angle from which it is seen. Opalescence is a common name for this phenomena. The color play may consist of big, distinct flashes of color or it may be made up of little, close-together flashes. The value of an opal is influenced by the frequency and intensity of the color flashes.
Opal is a kind of hydrated amorphous silica (SiO2nH2O); its water content can range from 3 to 21% by weight, but is typically between 6 and 10%. Unlike crystalline forms of silica, which are categorized as minerals, it is amorphous, making it a mineraloid. It is most frequently found with limonite, sandstone, rhyolite, marl, and basalt, although it may exist in the fissures of practically any type of rock. It is deposition at a very moderate temperature.
The Sanskrit word upala, which means "jewel," and its Greek derivation opállios, which means "to perceive a shift in hue," are said to be the origins of the term opal.
Both rare and ordinary opals come in a wide variety. Black opal, which has an opal with a dark blue, dark green, or black backdrop with a powerful play of color, is the most sought-after and stunning variety of opal. The Opal with a light colored body color (white, yellow, cream, etc.) with a strong color play is next in significance. The Mexican Fire Opal, a transparent to translucent deep-orange red variety of Common Opal, is also significant. Furthermore, Fire Opals can exhibit color play; they are known as Precious Fire Opals.
In addition to being categorized as either black or white opals, many valuable opals also have additional classifications depending on the distribution and pattern of their color play. Some of these names have more ancient origins, but others are brand-new trade names.
Opal doublets are thin slices of priceless opal bonded to a backing material. They are frequently used in jewelry. These gems offer the same play of color but are far less expensive than solid opals. To make opal doublets more scratch-resistant, a thin dome or coating of clear quartz may occasionally be applied to them (since Opal is a relatively soft gem). Opal triplets is another name for them.
Some Opals develop internal cracks as a result of a process called crazing. Being inconsistent and even surprising, craziness is an intriguing phenomena. Although it can happen at random, it frequently happens when an Opal is exposed to abrupt, bright light or when it is removed from moist circumstances and allowed to dry too quickly. When an Opal is subjected to vibration, such as when a gemstone is being cut and polished, crazing may also occur. Every gemstone "crazes" differently, and each gemstone crazes at a different rate. Given that different geographic regions are more or less prone to crazing, the origin is sometimes a deciding factor in a material's resistance to crazing.
In rare circumstances, a slow drying procedure over many months or even years can adequately stabilize the stone and allow it to be cut and polished with a far lower danger of crazing. All types of jewelry, particularly pendants and ring centerpieces, employ precious opals that have been cut and polished into cabochons. Fire opals are carved into a variety of gemstone shapes for jewelry. Boulder opal is another common kind that is used in jewelry, particularly as cabochons. Moreover, little decorative figures may be cut out of opal, particularly Common Opal.
Types of Opal
Andamooka Opal
Only the area of South Australia contains the Andamooka matrix opal. On Queen Elizabeth II's first visit to South Australia in 1954, a famous opal known as the Andamooka Opal was given to her. The opal was mined in 1949 in Andamooka. A stunning variety of reds, blues, and greens may be seen there.
Banded Opal
A kind of opal that has bands or layers of various colors is known as banded opal. It may be found in a variety of places, including Mintabie in South Australia, Coober Pedy in South Australia, and Lightning Ridge in New South Wales.
Black Opal
Any opal with a dark or black body color and "play of color" is referred described as a black opal. The most expensive opal variation is black opal. Moreover, the US, Ethiopia, Honduras, and Ethiopia are recognized sources of black opal.
Boulder Opal
As the name implies, boulder opals are mined from large ironstone boulders that are located underground in the Australian state of Queensland. Cracks and fractures in these stones give rise to thin veins of colorful opal. Due to the thinness of these color veins, opal cutters must leave the ironstone on the back of the opal in order to create a full-sized stone.
Cherry Opal
Cherry Opal has a vivid orange red color that pierces through a globular or botryoidal bulk that is otherwise colorless. Mexico has the greatest examples, in my opinion.
Chrysopal
Chrysopal is a kind of opal that resembles prase opal but has a golden-green hue.
Claro Opal
All stone levels contain clusters of the moderately valued gems known as claro opals.
Common Opal
Common Opal is a particular variety of opal that often only comes in a single hue and doesn't change color when exposed to light. Contrary to valuable opal, ordinary opal has transparent and translucent qualities that give it a "glassy" appearance.
Contra Luz Opal
Contra Luz, which translates from Spanish as "against the light," is a word used to describe the peculiar quality of this particular form of opal. It takes on a very lifeless yellow hue when illuminated by reflected light, like a mild Fire Opal.
Fire Opal
As water seeps into silica-rich lava, filling its cracks and hollows, fire opal is formed deep within ancient volcanoes. The lava keeps water inside itself while being subjected to such intense heat and pressure, creating these enchanted, sun-bright drops.
Flash Opal
This uncommon and exquisite substance is called "Satin-Flash" opal and is not frequently encountered. Pinpricks of spectral opalescence can be observed via translucent woven threads of denser opal material that are present in the clear opal.
Gilson Opal
The name "Gilson opal" is frequently used to describe imitation opals, such as Slocum stone, which are not only made in a lab but also include minerals that are absent from real opals.
Harlequin Opal
In nature, harlequin opals are quite uncommon. They have a design like the harlequin mask, which is characterized by large patches of cloth in various colors. The shimmering "patches" on Harlequin Opals are also unique and come in a variety of forms, some round and some obliquely square. Harlequin Opal is one of the rarest and most prized forms of Opal.
Honey Opal
from translucent to transparent Opal with a honey-colored, orange to orange-brown backdrop. It could or might not show color play.
Hungarian Opal
Discusses Opal according to ancient sources from Hungary and other countries in Europe, such the Czech Republic. Because of its inclusions, White Opal from other areas is occasionally referred to by this moniker as well.
Hyalite
The Greek word hialos, which means "glass," is where the term "hyalite opal" comes from. The second component of the name, opal, was inspired by the Greek term opallios, which is translated as "precious stone." These Greek words were employed by German geologist Abraham Gottlob Werner to identify the hyalite opal, which he discovered in the late 1700s. It goes without saying that other opal variations have existed for thousands of years, according to opal history. Hyalite opal is known by a variety of names. The terms "waterstone," "bacon opal," and even "sugar opal" have been used to describe it. glass-like radiance and rare fluorescence are reminiscent.
Jelly Opal
Opals with a jelly appearance are referred to as jelly opals. It is quite similar to crystal opal, however the hue of the opal is a tiny bit fainter, making it easier to see through. Nobby and seam opal varieties of jelly opal are available. Jelly opal is available in many grades, ranging from pale to dark opal.
Lemon Opal
Semi-opal from the Manhattan mine near Knoxville, Napa County, California, is sometimes referred to as lemon opal. The lemon opal exhibits a vivid yellow fluorescent reaction when exposed to long wave UV. Under short wave UV, the fluorescence is comparable but not as intense.
Lightning Ridge Opal
The most expensive black opals in the world are those from Lightning Ridge. The rare and highly sought-after black opal is only found in a few locations worldwide, including Lightning Ridge. Black opal, which differs from other opals in that it includes tiny amounts of carbon and iron oxide, produces an extremely dark stone with hints of blue, green, and red color play.
Mexican Fire Opal
The vivid red to orange body color of the Mexican Fire Opal, which is partially caused by iron oxide, earned it the name. This Mexican opal weighs less than other opals since it was mined there. These Mexican Fire Opals often have a single body color and lack the light and color flashes found in other opals.
Moss Opal
Moss opal is a form of opal that may be recognized by its inclusions, which are black, streaky, and moss-like. Dendrite, which means "tree" in Greek, is another name for it; this refers to its branching nature.
Nevada Opal
The Royal Peacock mines in Virgin Valley, Nevada, produce the most magnificent black opals on the planet. The clay strata in which Virgin Valley opals are discovered were created when volcanic ash filled an old lake millions of years ago. The ash also engulfed the neighboring woodlands. In the coves of the lake, branches, limbs, and decaying timber had gathered. As a reminder of their presence, the buried wood decomposed and left realistic voids.
Onyx Opal
Opal Jasper
Heal Your Emotions Stone. A natural jasper that originates in Africa is called African Opal Jasper. It is sometimes mistaken for variscite, a stone found in Queensland, Australia, and Nevada, Utah, which has a jelly-like sheen similar to turquoise.
Matrix Opal
Matrix opal is a gem substance in which play-of-color opal or valuable opal is evenly dispersed throughout the host rock. The priceless opal can appear as a "cement" between sediment grains, as a host material replacement, or as an infill for small vesicles. As "Type 3 Opal," matrix opal is frequently referred to.
Pinfire Opal
The term "pinfire opal" refers to opal that contains tiny spots of fire all throughout the stone. A pinfire opal was cut from material mined in Coober Pedy, Australia, and may be seen in the accompanying photograph on the right. The pinfire opal in the dark comes from the Constellation Mine near Spencer, Idaho. It measures 6 millimeters by 4 millimeters.
Precious Fire Opal
When light is reflected off of Fire Opal, an amorphous mineraloid made up of an aggregation of small hydrated silica spheres, it emits a prominent reddish-orange spectrum. Fire opal is frequently mistakenly referred to as a "mineral," although it is not one since it lacks a crystalline structure.
Precious Opal
Opal that exhibits a vibrant, intrinsic play of colors, which might be red, orange, green, or blue, is referred to as a precious opal. This color play results from the uniform packing of silica microspheres inside the mineral structure, which distorts white light.
Slocum Stone
One of the greatest fake opals available. Glass laminate with imbedded metal foil particles makes up Slocum stone.
Virgin Valley Opal
Thirty miles to the southwest of Denio, Nevada, is the remote region of Virgin Valley. Black fire opal is especially rare and only found there. The southernmost portion of Virgin Valley is where the Royal Peacock opal-bearing holdings are situated. The majority of the properties are located between 5,000 and 6,000 feet in elevation.
Wax Opal
White Cliffs Opal
Intense opal mining started in White Cliffs, Australia's first commercial opal field, in 1889. The first 20 years saw the most of the field's effort. Little droplets and ice crystals make up the majority of the material in an opal with a cloud; sunlight may pass through it rather readily and is dispersed evenly. These clouds have a stark white appearance. The amount of sunlight that passes through the cloud decreases as the size and concentration of the hydrometeors grow, leading to multiple scattering.
White Opal
Often known as 'milk' or 'milky' opals, Australian white opals are identified by their pale white or light body tone, displayed in the accompanying chart under "light opal". White opals, like all other opal types, are capable of displaying any color in the rainbow in a stunning dance of color.
Yowah Nut
The fabled "Yowah Nut," a valuable opal found in ironstone nodules or concretions, was discovered in the Southern Cross Mine. These "nuts" can grow to be 20 cm across. These are spherical or elliptical in form, and alternate concentric bands of light and dark brown siliceous ironstone may be seen.
Origins
Opal is found all over the world (in Brazil, Mexico, Honduras, and the western United States), but Australia is the source of 95% of the world's valuable opal. The majority of opal is produced in Australia. Other significant deposits may be found in Ethiopia, Sudan, Hungary, Honduras, Brazil, Mexico, and Nevada, Oregon, California, and Idaho in the United States.