Glossary of Terms:





A mining town in South Australia, situated 520km north of Adelaide that produces precious opal and treating matrix opal. Opal was discovered in Andamooka in 1930 in the form of floaters below what is now known as Treloar Hill. The first opal miners of the area were Treloar and Evans, and their first recorded production of precious opal was in 1933.


See our collection of Andamooka Opal.

Andamooka Matrix: (Class C2)

A very white, porous opal found only in Andamooka which is dyed black, giving the play of colors a black background in which to weave their magic. This was done as early as the 1950's by soaking the opal in a sugar solution first, then sulfuric acid which burnt the sugar and turned it black. Andamooka matrix is very rare and sought after today.

Arrow Head:

The pointed head or striking tip of an arrow.


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Baguette Cut:

A rectangular step cut.


A piece a jewelry worn around the wrist.

Base/Body Color:

The background color of an opal, not taking into account the play of colors on or near the surface.

Base Metal:

Any of certain common metals (as distinct from precious metals) that are coated or plated with precious metals.

Belemnite: (Class A)

A conical fossil tapering to a point at one end with a conical cavity at the other end containing (when unbroken) a small chambered phragmocone from the shell of any of numerous extinct cephalopods of the family Belemnitidae. Found in seas and oceans of the Mesozoic era, between 66-245 million years ago.


View our collection of Opal Belemnites.



See Belemnite.

Belt Buckle:

A clasp used to fasten and adjust a belt.


Belly Stud:

A stud that is worn through the belly button.

Bezel Set:

This is a type of setting where the gemstone is set into a piece of jewelry and completely surrounded by a metal perimeter. The outer rim of the metal is burnished, or bent over and smoothed out around the girdle of the gemstone. Bezel settings are extremely secure.

Black Crystal Opal:

A solid opal that is translucent to transparent with a play of color, which when viewed from the top is graded as black opal.


Black Opal:

A solid opal that is opaque and has a play of color against a black background when viewed from above.


View our stunning collection of Black Opal.

Body Art:

Jewelry associated with body piercing, e.g. nose ring, belly stud etc.


Boulder Doublet: (Class B)

A two part assembled gem made of precious opal (transparent to translucent) and an opaque ironstone backing glued to it (Queensland boulder), giving the finished opal a black opal look. Doublets are an inexpensive way to purchase high quality opal because only a thin piece of opal is used.

Boulder Opal:

A seam or patches of precious opal still attached to the host rock in which the opal formed. Highly valued and sought after for its brilliant colors and patterns. Most boulder opal is mined in Queensland, Australia.


View our complete range of Boulder Opal.


A piece of jewelry worn around the wrist.


An alloy of copper and zinc.

Brilliant Cut:

A type of cut which is generally composed of triangular and kite shaped facets.


Broad Flash:

A pattern in which large sheets of color cover most (if not all) of the opal's surface.


View all available opals with a Broad Flash Pattern.



An alloy of Copper and Tin and sometimes other elements.


A decorative pin worn by women.


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A solid opal (or other gemstone) cut into an elliptical, round or polygonal shape with a flat base and a domed top. A stone cut in this manner is described as being cut 'en cabochon'.



An opal that has been cut to a standard dimension (example 9mm x 7mm).



A unit of measure used to express weight of gemstones (1carat = 0.2 grams).



See Opal Carving.



A piece of jewelry that fits tightly around the neck.



The degree of transparency of an opal.


Claw Set:

This is a type of setting where the gemstone is set into a piece of jewelry with fine wire claws (gold, silver etc). The claws are bent over the stone and hold it in place. Claw settings are known to sometimes catch on fabric but remain very popular because they showcase almost the whole gemstone.



The color or combination of colors exhibited in precious opal; does not take into account the color of the stone itself, but only the play of colors within the stone. If one color is very predominant in an opal then the color of that opal will be that color e.g. an opal that is predominantly red with a little blue will be classed as red. If two colors are predominant (e.g. red and gold), then it shall be classed as red/gold. The minor colors will be listed in the description. If an opal has three dominant colors then it is classed as a multicolor.

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Color Bar:

A layer of color in opal.


Coober Pedy:

An opal-mining town in central South Australia. Coober Pedy lies in the Stuart Range, 750km north of Adelaide. Since the discovery of precious opal there in 1915, Coober Pedy has been the world’s largest producer of precious opal.


The first white person to discover opal in the area was a 14 year old boy by the name of J.S. Hutchinson, looking for water to take back to his father’s camp. His Father, along with a group of other men were prospecting in the area for gold. Big Flat was the first established opal field in 1916. The underground style of living gave Coober Pedy it’s name, which is derived from the Aboriginal ‘kupa piti’ meaning ‘white mans burrow’. Today, opal workings extend more than 40km north and 10km south of the township.


View our complete range of Coober Pedy Opal.



A ductile malleable reddish-brown corrosion resistant diamagnetic metallic element (Cu).


Crystal Opal:

Transparent to translucent solid opal with flashes of color; highly valued due to the brilliance of its colors and the fact that many layers of color can be seen within the stone.


View our entire collection of Crystal Opal.



A pair of linked buttons used in the cuffs of a shirt.


Cut Opal:

Opal that has been cut, sanded and polished and is ready to be set into jewelry.


Browse our range of Cut Opal.


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Dark Crystal:

Dark crystal opal is a transparent to translucent type of opal whose base is not a clear crystal but a dark or smoky crystal.


View our entire collection of Dark Crystal Opal.



A deviation in the direction of a wave of light.


Doublet: (Class B)

See Opal Doublet.


Drop Earring:

A style of earring that hangs below the ear.


Dot Painting:

The aborigines of Australia have a very unique and beautiful method of creating stunning paintings by using many small dots to make the drawing, usually telling a story from the past.


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Any type of jewelry that is designed to be worn on ones ears.


View our entire collection of Opal Earrings.


Emerald Cut:

The name used for a rectangular cut with truncated corners. This style of cut was apparently developed especially for emeralds but is now used to facet many different gemstones.


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Fine Silver:

A soft white precious metallic element (Ag).



Refers to the diffracted color play of an opal.



A pattern in opal that is very bright.



Pieces of opal or nobbies eroded from their original host rock and found in creeks, water courses and on low lying land below mesas (flat top hills) or escarpments.


Fossil Opal:

Opal that has filled cavities in the ground left behind by once living organisms e.g. opal belemnite, opal shell, opal shell-skin, opal snail, opal specimen etc.


View our entire collection of Fossil Opal.


Free Shape:

An opal that has been cut according to the natural shape of the stone.



An opal that has been cut into an irregular shape.


Full Color:

Opal that displays a play of color throughout the whole stone from edge to edge.


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Gem Quality:

This is the finest grade opal available.


Gold Plated:

Jewelry that consists of a base metal with a thin coating of gold; usually produced by electroplating.


Gray Base:

A solid opal that is opaque with a gray base/body color.


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The rarest and most sought after pattern in opal. The colors have formed naturally into a checkerboard pattern.


Hoop Earrings:

A circular band of precious metal with or without a gemstone worn on the ears.


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Non-opal within precious opal. These can be grains of sand or other natural materials. Inclusions can greatly affect the price of opal in an upward and downward manner and sometimes not at all. If an inclusion is deemed to detract from the stone, then the value is greatly reduced. If however, an inclusion adds a new character or dimension to an opal, then it can increase the value immensely.


Inlay Setting:

A solid opal fitted into a cavity and cemented into place.


Irregular Pattern:

A pattern within opal lacking uniformity or symmetry.


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An opaque form of quartz.


Jelly Opal:

A transparent type of precious opal (similar in appearance to crystal opal)which does not display a defined, regular pattern when idle, but when rolled or moved has flashes of color.


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An opal mining field situated around 200km north of Coober Pedy. Lambina is a small camp on a large station in northern South Australia. Conditions are very difficult due to it's isolation and extreme weather conditions, especially in the summer months when temperatures often exceed 45C.


Lightning Ridge:

A mining town in New South Wales famous for its black opals (mostly nobbies and some seam). The first parcel of opal from Lightning Ridge was mined and sold in 1903 by Charlie Nettleton. He had difficulty selling the parcel because the opal was so dark. By 1908 black opal mined in Lightning Ridge was fetching 50 times the price it did in 1903. Today, Lightning Ridge produces the worlds most sought after and highly valued black opal.


View our entire range of Lightning Ridge Opal.


Loose Opal:

Loose opal refers to cut and polished precious opals.


View our entire range of Loose Opals.

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Marquise Cut:

The name given to a cut which is pointed at both ends, with the sides being portions of a circle.



A host rock within which something originates (From the Latin word womb). See also Andamooka Matrix.


Metal Type:

Describes the purity and type of metal used in a particular piece of jewelry.


Milky Opal:

Opal with a white base/body color.

See White Opal.



A mining town situated 350km northwest of Coober Pedy in northern South Australia. The first white opal miners came to the area in the early 1920’s but the local Aboriginals had sold black opal, which more than likely came from from Mintabie, as early as 1915. Mintabie was the largest opal-producing field in Australia from 1985 to 1989 in value, although the greatest volume of precious opal still comes from Coober Pedy.


View our entire selection of Mintabie Opal.


Mohs' Scale:

The Mohs Scale of Hardness (1-10) came into accepted use around 1812. It was conceived by the German mineralogist Frederick Mohs in which 1 represents the hardness of talc and 10 represents the hardness of diamond. The hardness of a mineral is a measure of it's resistance to scratching. Opal has a hardness in Mohs' Scale of between 5.5 and 6.5. The scale below includes ten common substances for comparison.


1: Talc__Can be scratched with a fingernail
2: Gypsum__Can be scratched with a fingernail
3: Calcite__Can be scratched with a penny
4: Fluorite__Easily scratched with a knife
5: Turquoise__Can be scratched with a knife
6: Opal__Can be scratched with a steel knife
7: Amethyst/Quartz__ Scratches window glass
8: Topaz__Scratches anything 8 or below
9: Ruby/Sapphire__Scratches anything 9 or below
10: Diamond__Scratches all



Small pieces of opal fitted alongside each other.



An opal which displays at least three distinct colors.


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Natural Cut:

This type of cut is one where the opal has been left as true to its natural shape as possible.



A cord or chain (often bearing gems) worn around the neck.



Something worn around the neck.


Night Stone:

An opal which is displays a very bright play of color in low light.



Pieces of opal derived from erosion of a vertical or level. The term is rarely used in South Australia, but commonly used at Lightning Ridge and refers to opal found in the form of small nodules.


Number of Pieces:

The total number of pieces in a particular parcel.


Number of Stones:

The total number of stones in a particular parcel.

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Geological Definition: Opal is a non crystalline form of the mineral silica which, despite its amorphous structure, displays an amazing degree of internal organization. Includes all hydrates of silica, SiO2 nH2O, including synthetic, natural precious and common opal but not imitation material. Alternative term is opaline silica.

Opal miners generally restrict the use of the term opal to precious opal. Opal that does not exhibit a play of colors is referred to as potch. See also Potch.


View our entire collection of Opals.



Opal Belemnite: (Class A)

Opal that has flowed into a cavity in the ground left behind by a belemnite.


Opal Carving:

A piece of opal that has been carved into a particular shape.


Opal Category:

This is the category the opal being viewed falls into, e.g. black opal, crystal opal, black crystal opal, jelly opal, milky opal, dark crystal, boulder doublet, matrix, boulder opal, (Gem, A , B and C grade for triplets) etc.


Opal Chips: (Class A)

Small pieces of rough opal.

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Opal Doublet: (Class B)

A two part assembled stone consisting of precious opal cemented to another stone; this can be opal or another stone. See also Shell Skin Doublet, Boulder Doublet.


View our range of Opal Doublets.


Opal Potch:

See Potch.


Opal Shell: (Class A)

Opal that has filled the cavity left behind by a sea-shell.


View our entire collection of Opal Shells.


Opal Shell Skin: (Class A)

Opal that has flowed into the cavity left behind by a sea-shell which was open and thus the middle of the shell filled with soil and only the cast left behind by the shell itself filled with opal.


View our collection of Opal Shell Skins.


Opal Size:

The outer dimensions (length x width) of a piece of opal expressed in millimeters.

(25.4mm = 1Inch)


Opal Snail: (Class A)

Opal that has filled the cavity in the ground left behind by a sea-snail.


Opal Specimen: (Class A)

A piece of opal that is more suited to be kept as a specimen rather than be cut for jewelry.


Opal Triplet: (Class B)

A cut opal consisting of three layers; Clear quartz on top, a thin slice of precious opal in the center and a black base all glued together and shaped. Triplets are very good value for money because only a thin piece of precious opal is used. All triplets are backed onto a black background thus giving them the appearance of black opal.


View our range of Opal Triplets.



Not see through.



The geographic location where a particular opal was mined. All our opal has been mined in Australia. See also Andamooka, Coober Pedy, Lambina, Lightning Ridge, Mintabie, Yowah.

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Painted Lady:

A boulder consisting of precious opal laid in a sheet on one side.



The pattern made by the play of color in an opal. Varieties of pattern include, small, medium and large pattern; pinfire, rolling flash, broad flash, harlequin


Pattern Type:

The type of pattern displayed in an opal. See also Pattern


Pear Shape:

A shape that starts off at a point and widens. Also called a teardrop



An adornment that hangs from a necklace.


View our entire collection of Opal Pendants.



Various alloys of tin with small amounts of other metals (especially lead).



This is the amount of individual pieces making up the parcel.



A type of pattern which consists of small, pinpoint circles of color.


View all available opals with a Pinfire Pattern.


Pipe: (Class A)

Miners term for Belemnite. See Belemnite.

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A heavy precious metallic element; gray-white and resistant to corroding. Occurs in some nickel and copper ores and is also found native in some deposits.



A now extinct sea reptile distinguished by a very long neck, a small head, paddle-shaped limbs and a short body and tail. Growing to a total length of about 12 meters when mature. Plesiosaurus roamed the inland seas of Australia and other places during the Jurassic and Cretaceous era.


Polished Opal:

Precious opal that has been cut into any shape, sanded and polished and is ready to be set into jewelry.


Browse our entire range of Polished Opal.



Can be black, white, crystal, honey or blue opal that displays no play of color.

Potch and Color:

Opal that consists of mainly potch with only a small amount of color in between.


Precious Opal:

Opal which displays a play of color in a distinct pattern.



The selling price of a product. This price does not include shipping costs, or any taxes or duties (if any) that might be payable on arrival to you. Shipping fees will be calculated for you in your cart according to destination and chosen shipping method. Duties and taxes payable vary between countries. If you are unsure if any duties or taxes will apply to you, please check with your local customs office.


Price per gram:

This is the price per gram and not the total price of a parcel. The total price is equal to the price per gram multiplied by the number of grams.


Product Type:

This is the type of product within the category you are viewing, e.g. solid opal, opal doublet, opal triplet, opal shell, opal shell-skin, opal belemnite, opal ring, opal pendant, dot painting etc.


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A hard metallic element that is one of the platinum group and is found in platinum ores; used in alloys with platinum (Rh).


Rhodium Plated:

Jewelry that consists of a base metal with a thin coating of rhodium; usually produced by electroplating.


Ribbon Pattern:

A pattern in opal that resembles ribbons of color. Opals displaying this characteristic are very rare and highly valued.


Ring Size:

By default, ring size for custom opal jewelry is shown as US Ring Size. To convert your local ring size to US size, please click the ‘International Ring Sizes’ link on the page of the inlay opal ring you are viewing and our ring size converter will pop-up. Just match your local ring size to the US ring size from our chart.


Rolling Flash:

A color pattern in which sheets of color roll across the surface of the opal as it's moved or tilted.


View all available opals with a Rolling Flash.


Rough Opal: (Class A)

Precious opal in its natural state. May have been snipped from the host rock and tumbled to minimize waste but has not been ground, polished or shaped at all.


View our Rough Opal Parcels.


Rubbed Opal: (Class A)

A term usually referring to nobbies of Lightning Ridge opal whose surface has been ground or sawn in order to expose the color of the stone.


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A sedimentary rock consisting of sand consolidated with some cement (clay or quartz).


Seam Opal:

Opal formed in a horizontal or near horizontal layer.



Setting Type:

Setting refers to the style by which a gemstone is held to an item of jewelry e.g. bezel set, claw set, inlay setting etc.



This term refers to the shape that an opal has been cut into. Shapes can be oval, round, teardrop, freeform, free shape etc.


Shell: (Class A)

See Opal Shell.


Shell Skin: (Class A)

See Opal Shell Skin.


Shell Skin Doublets: (Class B)

A doublet in which the precious opal is opalised shell skin. The backing can be potch or other materials.



The physical size of a product: 1 inch = 25.4mm / 1 inch = 2.54cm


Snail: (Class A)

Opalised mould left behind by a sea snail.


Solid Opal: (Class A)

A solid gem cut from natural precious opal with no other type of stone present (cemented or otherwise).


View our comprehensive range of Solid Opal.



See Opal Specimen.

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Stainless Steel:

Steel containing chromium that makes it resistant to corrosion.


Sterling Silver:

A silver alloy with no more than 7.5% copper.



The total number of opals in the parcel.


Straw Pattern:


Stud Earring:

A type of earring that that does not hang down below the ear. It has an outer face and a pin attached to the rear that goes through the ear.


Style of Cut:

Describes the top surface shape of an opal, e.g. flat, cabochon, uneven, undulating, natural cut etc.


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A term used to describe an opal or other precious gemstone that has been cut into a pear-shape.


View our entire range of opals that have been fashioned into teardrops.



The outer thickness of a stone measured from the back to the front (face) of the stone.


Tie Pin:

A pin used to hold a tie in place.



This is the approximate amount of time needed to custom make your order (not including delivery time). Times will generally be less than stated but not longer.



A light, strong, lustrous corrosion resistant metallic element (Ti).


Toe Ring:

A ring that is worn on the toes.


Total Price:

The total sale price of a product (excluding postage and handling).






The ease with which one can see through an opal. See also Transparent, Translucent and Opaque



See through.


Triplet: (Class B)

See Opal Triplet.


Type of Opal:

See Fossil Opal.


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Rising and falling.



Not level.




Vertical Opal:

Opal formed in a vertical or near vertical layer.





The total weight of a product. For all cut opal and fossil opal weight is expressed in carats (5carats = 1gram), and for rough opal and opal jewelry it is expressed in grams.


White Cliffs:

A mining town in New South Wales.


White Opal:

Common form of gem quality opal which is opaque and possesses a white body color. White opal is often referred to as milky opal.


View our collection of White Opal/Milky Opal.


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A mining town in Queensland.


Yowah Nut:

An unusual boulder matrix found only in Yowah.


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A bluish-white lustrous metallic element (Zn).




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