Australian Boulder Opal for Sale | Natural Opals in Stock

We're proud to present our unique selection of natural Boulder Opal for sale. Boulder Opal has an earthy brown base-color mixed with the whole color spectrum of opal. This is the perfect gemstone for jewelry designers and hobby jewelers as well. We stock Boulder Opals in a large variety of shapes, sizes and price ranges. Use the filters on this page to quickly select the perfect fitting Boulder Opal for your jewelry needs. We ship our gemstones worldwide with a variety of shipping options.

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Gemstones A-Z

Actinolite Cat's Eye 59 Agate 812 Agate Geode 19 Almandine Garnet 35 Amazonite 213 Amethyst 3,127 Amethyst Geode Slice 80 Ametrine 206 Ammolite 452 Andalusite 204 Andesine Labradorite 149 Apatite 564 Aquamarine 91 Aventurine 132 Azotic Topaz 13 Azurite 21 Black Opal 329 Bloodstone 255 Boulder Opal 216 Carnelian 91 Cat's Eye Apatite 39 Cat's Eye Aquamarine 18 Cat's Eye Gemstones 1,112 Cat's Eye Moonstone 67 Cat's Eye Opal 168 Cat's Eye Scapolite 97 Chalcedony 124 Charoite 166 Chocolate Opal 75 Chrome Diopside 1 Chrysoberyl 100 Chrysoberyl Cat's Eye 178 Chrysocolla 63 Chrysoprase 33 Citrine 4,248 Color Change Gemstones 833 Color-Change Diaspore 714 Color-Change Fluorite 59 Color-Change Garnet 60 Coral 293 Demantoid Garnet 248 Dendritic Agate 241 Diamond 697 Druzy Amethyst 5 Druzy Azurite 21 Druzy Citrine 51 Druzy Variscite 132 Emerald 882 Enstatite 5 Fire Agate 338 Fire Opal 169 Fluorite 205 Fossil Coral 330 Garnet 5,849 Golden Beryl 184 Grandidierite 186 Grossularite Garnet 50 Hawk's Eye 1 Hematite 372 Hemimorphite 46 Hemimorphite Druzy 46 Hessonite Garnet 2,250 Hiddenite 17 Howlite 142 Idocrase 27 Imperial Topaz 12 Iolite 171 Jade Gemstones 319 Jadeite 319 Jasper 1,362 Kornerupine 244 Kunzite 439 Kyanite 698 Labradorite 664 Lapis Lazuli 341 Larimar 156 Lepidolite 49 Malachite 245 Malaya Garnet 149 Mali Garnet 12 Maw-Sit-Sit 132 Moonstone 955 Morganite 895 Moss Agate 69 Mother Of Pearl 102 Mystic Quartz 417 Mystic Topaz 28 Nuummite 121 Obsidian 248 Onyx 288 Opal 1,226 Opal Doublet 5 Opal In Matrix 20 Peanut Wood 15 Pearl 19 Peridot 1,382 Pietersite 647 Prehnite 837 Psilomelane Dendrite 25 Pyrite 16 Pyrope Garnet 1,854 Quartz 1,323 Quartz Cat's Eye 85 Quartz With Hedenbergite 9 Quartz With Marcasite 190 Rainbow Moonstone 624 Rainbow Pyrite 183 Rhodochrosite 159 Rhodolite Garnet 458 Rhodonite 38 Rose Quartz 748 Rubellite Tourmaline 12 Ruby 1,261 Ruby In Fuchsite 93 Ruby-Zoisite 220 Rutile Quartz 540 Sapphire 5,124 Scapolite 97 Scolecite 34 Seraphinite 50 Serpentine 80 Sillimanite 73 Sillimanite Cat's Eye 401 Smithsonite 1 Smoky Quartz 1,069 Snowflake Obsidian 35 Sodalite 34 Spectrolite 147 Spessartite Garnet 382 Sphalerite 360 Sphene 506 Spinel 959 Star Diopside 8 Star Garnet 50 Star Gemstones 847 Star Moonstone 98 Star Rose Quartz 18 Star Ruby 257 Star Sapphire 413 Star Sunstone 3 Strawberry Quartz 951 Sunstone 508 Tanzanite 838 Tiger's Eye 861 Tiger's Eye Matrix 167 Topaz 4,604 Tourmaline 2,408 Tsavorite Garnet 241 Turquoise 97 Uvarovite Garnet Drusy 60 Variscite 8 Zircon 2,063

Bi-color

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Blue

Brown

Golden

Gray

Green

Multicolor Boulder Opal

Orange

Pink

Purple

Red

Turquoise

Violet

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Yellow

Boulder Opal Single

Boulder Opal Pairs

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Boulder Opal Faceted

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Photos are of Actual Products for Sale

25.5 ct Trillion Boulder Opal, 22.1 x 21.4 mm From Australia

Natural Boulder Opal, Qty: 1 pc | 25.50 carat weight Boulder Opal

25.50ct1 Piece

$ 127.50

22.1 x 21.4 mm

Item Description
Stone Type:	Loose Boulder Opal
Boulder Opal Weight:	25.50 ct Boulder Opal
Boulder Opal Shape:	Trillion Cabochon Boulder Opal
Boulder Opal Size:	22.1 x 21.4 mm Boulder Opal
Boulder Opal Color:	Multicolor Boulder Opal
Boulder Opal Clarity:	Opaque Boulder Opal
Boulder Opal Origin:	Australia Boulder Opal
Boulder Opal Treatment:	Untreated
Boulder Opal Quantity:	1
Boulder Opal Certificate:	GemSelect
Product Description:

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17.24 ct Trillion Boulder Opal, 21.2 x 17.4 mm From Australia

Natural Boulder Opal, Qty: 1 pc | 17.24 carat weight Boulder Opal

17.24ct1 Piece

$ 86.20

21.2 x 17.4 mm

Item Description
Stone Type:	Loose Boulder Opal
Boulder Opal Weight:	17.24 ct Boulder Opal
Boulder Opal Shape:	Trillion Cabochon Boulder Opal
Boulder Opal Size:	21.2 x 17.4 mm Boulder Opal
Boulder Opal Color:	Multicolor Boulder Opal
Boulder Opal Clarity:	Opaque Boulder Opal
Boulder Opal Origin:	Australia Boulder Opal
Boulder Opal Treatment:	Untreated
Boulder Opal Quantity:	1
Boulder Opal Certificate:	GemSelect
Product Description:

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12.73 ct Trillion Boulder Opal, 16.6 x 15.7 mm From Australia

Natural Boulder Opal, Qty: 1 pc | 12.73 carat weight Boulder Opal

12.73ct1 Piece

$ 63.65

16.6 x 15.7 mm

Item Description
Stone Type:	Loose Boulder Opal
Boulder Opal Weight:	12.73 ct Boulder Opal
Boulder Opal Shape:	Trillion Cabochon Boulder Opal
Boulder Opal Size:	16.6 x 15.7 mm Boulder Opal
Boulder Opal Color:	Multicolor Boulder Opal
Boulder Opal Clarity:	Opaque Boulder Opal
Boulder Opal Origin:	Australia Boulder Opal
Boulder Opal Treatment:	Untreated
Boulder Opal Quantity:	1
Boulder Opal Certificate:	GemSelect
Product Description:

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5.28 ct Trillion Boulder Opal, 17.3 x 15.9 mm From Australia

Natural Boulder Opal, Qty: 1 pc | 5.28 carat weight Boulder Opal

5.28ct1 Piece

$ 36.96

17.3 x 15.9 mm

Item Description
Stone Type:	Loose Boulder Opal
Boulder Opal Weight:	5.28 ct Boulder Opal
Boulder Opal Shape:	Trillion Cabochon Boulder Opal
Boulder Opal Size:	17.3 x 15.9 mm Boulder Opal
Boulder Opal Color:	Multicolor Boulder Opal
Boulder Opal Clarity:	Translucent Boulder Opal
Boulder Opal Origin:	Australia Boulder Opal
Boulder Opal Treatment:	Untreated
Boulder Opal Quantity:	1
Boulder Opal Certificate:	GemSelect
Product Description:

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33.93 ct Trillion Boulder Opal, 26.7 x 21.3 mm From Australia

Natural Boulder Opal, Qty: 1 pc | 33.93 carat weight Boulder Opal

33.93ct1 Piece

$ 224.47

26.7 x 21.3 mm

Item Description
Stone Type:	Loose Boulder Opal
Boulder Opal Weight:	33.93 ct Boulder Opal
Boulder Opal Shape:	Trillion Cabochon Boulder Opal
Boulder Opal Size:	26.7 x 21.3 mm Boulder Opal
Boulder Opal Color:	Multicolor Boulder Opal
Boulder Opal Clarity:	Opaque Boulder Opal
Boulder Opal Origin:	Australia Boulder Opal
Boulder Opal Treatment:	Untreated
Boulder Opal Quantity:	1
Boulder Opal Certificate:	GemSelect
Product Description:

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13.97 ct Trillion Boulder Opal, 20.4 x 12.9 mm From Australia

Natural Boulder Opal, Qty: 1 pc | 13.97 carat weight Boulder Opal

13.97ct1 Piece

$ 76.84

20.4 x 12.9 mm

Item Description
Stone Type:	Loose Boulder Opal
Boulder Opal Weight:	13.97 ct Boulder Opal
Boulder Opal Shape:	Trillion Cabochon Boulder Opal
Boulder Opal Size:	20.4 x 12.9 mm Boulder Opal
Boulder Opal Color:	Multicolor Boulder Opal
Boulder Opal Clarity:	Translucent Boulder Opal
Boulder Opal Origin:	Australia Boulder Opal
Boulder Opal Treatment:	Untreated
Boulder Opal Quantity:	1
Boulder Opal Certificate:	GemSelect
Product Description:

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19.83 ct Trillion Boulder Opal, 22.8 x 21.2 mm From Australia

Natural Boulder Opal, Qty: 1 pc | 19.83 carat weight Boulder Opal

19.83ct1 Piece

$ 65.44

22.8 x 21.2 mm

Item Description
Stone Type:	Loose Boulder Opal
Boulder Opal Weight:	19.83 ct Boulder Opal
Boulder Opal Shape:	Trillion Cabochon Boulder Opal
Boulder Opal Size:	22.8 x 21.2 mm Boulder Opal
Boulder Opal Color:	Multicolor Boulder Opal
Boulder Opal Clarity:	Opaque Boulder Opal
Boulder Opal Origin:	Australia Boulder Opal
Boulder Opal Treatment:	Untreated
Boulder Opal Quantity:	1
Boulder Opal Certificate:	GemSelect
Product Description:

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6.17 ct Trillion Boulder Opal, 14.2 x 13.9 mm From Australia

Natural Boulder Opal, Qty: 1 pc | 6.17 carat weight Boulder Opal

6.17ct1 Piece

$ 30.85

14.2 x 13.9 mm

Item Description
Stone Type:	Loose Boulder Opal
Boulder Opal Weight:	6.17 ct Boulder Opal
Boulder Opal Shape:	Trillion Cabochon Boulder Opal
Boulder Opal Size:	14.2 x 13.9 mm Boulder Opal
Boulder Opal Color:	Multicolor Boulder Opal
Boulder Opal Clarity:	Opaque Boulder Opal
Boulder Opal Origin:	Australia Boulder Opal
Boulder Opal Treatment:	Untreated
Boulder Opal Quantity:	1
Boulder Opal Certificate:	GemSelect
Product Description:

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This Page in Other Languages

Opals really are a mixed bag of gemstones. Just some of the varieties include white opals, black opals, fire opals, pink Peruvian opals, hyalite opals and I could go on for quite a while yet.

Boulder Opals are one of the better known gemstones in this family. They are distinct from most other opals by still being connected to the rock in which they formed.

This means that the thin slivers of precious opal have a substantial foundation so it is much more durable and the dark rock is a perfect background for the vibrant play-of-color.

Boulder Opal Colors

There is no such thing as a typical Boulder Opal color. Every gemstone is different in both shape and color with every color of the rainbow a possibility. Not only can Boulder Opals feature all colors but as the stone moves other colors can flash or dance before your eyes.

The precious opal material that forms in cracks and crevices within the host rock is made up of tiny spheres in which light can bounce around creating the dazzling colors.

Larger spheres bring out the red colors while smaller spheres show up as blue. Large spheres are rarer so any Boulder Opal showing colors such as red or orange - the ones at the top of the rainbow - will be more expensive than the blues and greens found at the bottom.

Boulder Opal Species

Boulder Opals are just one of many types of opals found around the world. Some have the famous play-of-color while others are a single color but all are fascinating gemstones.

Just a few of the more well-known ones are:

White Opals
Black Opals
Fire Opals
Matrix Opals
Hyalite Opals
Cat's Eye Opals

And there are many more besides.

Boulder Opal Price

Like most gemstones, it is the color of the Boulder Opal that is the number one consideration when appraising its price. However, there are a couple of extra considerations to bear in mind with this stone.

There is the coverage - a gemstone that has a large area of precious opal spread over the surface will get a higher price than one with a few spots here and there.

A contrast between a dark background and a bright color can increase the value of the opal.

As we mentioned earlier, some colors are rarer than others and a simple rule is to work your way down the rainbow with the red at the top being the most expensive and the purple at the bottom being the least expensive.

This is a very basic rule which can vary from stone to stone with the coverage and contrast aspects to bear in mind.

Carat Weight

Boulder Opals are precious opal material still connected to the base rock so they tend to be quite large gemstones. They can also be irregular shapes to incorporate as much of the naturally occurring opal as possible.

Pricing Boulder Opals on carat weight can be a little tricky as there is often a lot of ironstone or sandstone left after cutting and polishing. It may be a very thick and heavy stone with just a thin veneer of colored opal on the front.

It is best to choose your Boulder Opal based on physical size - the length, width and height - rather than carat size. As a very rough guide, Boulder Opals can be anything from $2 to $15 per carat for basic colors up to $50 to $800 per carat for gemstones with outstanding colors, depending on color, coverage and contrast.

Treatments

Generally, Boulder Opals are a completely natural gemstone with no treatment other than cutting and polishing.

As we have said, the contrast between the opal and the rock background can increase the value so there have been cases of the base rock being smoked or soaked in sugar to darken up the body but this is not very common in Boulder Opals and happens more with Black Opals.

Sometimes the precious opal can come loose from the rock backing and can be reattached with glue or resin. This would be difficult to spot unless a sudden impact or high heat breaks the seal but we are not aware of this being a serious problem.

Any treatment received by any of our gemstones is clearly disclosed.

Where are Boulder Opals found?

Basically all Boulder Opals come from central Queensland. This may not sound that impressive but it is an area about the size of California and home to about 200,000 people (and lots of kangaroos, rock wallabies, goannas and spiders).

What jewelry is Boulder Opal suitable for?

Boulder Opals have a rating of 5.5 to 6.5 on Mohs hardness scale. This would usually make them a little bit fragile for many jewelry items and not suitable for daily wear, however Boulder Opals are still attached to the durable rocks they formed in so are much tougher than the rating would suggest.

Large and striking Boulder Opals cut into interesting odd shapes can help create wonderful and unique jewelry items, especially pendants, brooches and earrings where durability is not such an issue. Boulder opal rings in protective settings can be particularly striking items of jewelry.

Birthstones and Anniversaries

Boulder Opals are the birthstone of October and would make an ideal gift for anyone celebrating a birthday in that month.

A Boulder Opal is the traditional gemstone gift for the 14th wedding anniversary.

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Gemstone Information

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