12.18 ct Boulder Opal Blue Green front face view Australian opal gemstone Opal Galaxy product image
12.18 ct Boulder Opal Blue Green angled view Australian opal gemstone Opal Galaxy product image
12.18 ct Boulder Opal Blue Green back view Australian opal gemstone Opal Galaxy product image
12.18 ct Boulder Opal Blue Green detail view Australian opal gemstone Opal Galaxy product image
12.18 ct Boulder Opal Blue Green detail view Australian opal gemstone Opal Galaxy product image

This 12.18ct natural Australian boulder opal from Winton, Queensland displays blue and green fire concentrated within a defined central color bar, surrounded by a softer light blue host. The freeform polished cabochon highlights natural contrast between the vivid color zone and surrounding ironstone.

About Boulder Opal

Boulder opal forms within ironstone, creating natural patterns where vibrant opal color contrasts with the host rock. Stones with defined color bars are valued for their natural structure and visual contrast.

Jewelry Use

This opal is suited as a loose gemstone for custom ring or pendant settings. The elongated freeform shape allows flexibility in design while maintaining strong visual focus on the central color.

October Birthstone

Boulder opal is part of the Australian opal family and is associated with October birthstone jewelry. Each stone displays natural variation in color and pattern.

Authenticity

100% natural solid Australian opal. No treatments. No doublets or triplets.


Learn more

Boulder Opal from Winton | What Makes an Opal Valuable| Australian Opal Buying Guide

Browse all Boulder Opal collection or contact us with questions.

Shipping Updates - March 2026

Latest international delivery information from Australia Post and FedEx.

USA Tariffย 

USA customers do not need to pay any tariffs on their purchase. Opal Galaxy covers all tariff charges to the USA, with no additional government fees added after checkout.

Delivery Status

USA: No delays
Asia: No delays
UK: Minor delays possible (Complimentary EMS Express upgrade)
Europe: Minor delays possible (Complimentary EMS Express upgrade)
Middle East: Shipping temporarily suspended - Please contact us to discuss shipping arrangements before purchase.

Shipping Information

All shipping includes complimentary insurance.

Registered Shipping $15 under $200
Free Registered Shipping over $201
Free Worldwide EMS Express Shipping over $1000
Free Worldwide FedEx Shipping over $4000
Extra Cost $25 EMS Shipping Upgrade under $200
Extra Cost $10 EMS Shipping Upgrade under $999
Extra Cost $100 FedEx Shipping Upgrade under $3999

Please view ourย Shipping Policyย page for more information.

7 day return and refund policy.
Please view ourย Return and Refundย page for more information.

We offer a lifetime guarantee for natural cracks that may form in our opals.
There is a very low chance that this can happen, however occasionally it might.
Our guarantee excludes any opals sold with existing fractures.
Please view our Terms and Conditions.

Caring for Your Australian Opal

Opal Jewelry

Important: Opals Are Fragile Gemstones
Opals are softer than sapphires, rubies, or diamonds and will crack or chip if struck hard against solid surfaces.

Always remove opal jewelry before:
Sports or physical activities
Manual labor, gardening, or gym workouts
Household tasks where impact is possible (lifting, moving furniture, etc.)

Even a minor knock during everyday wear can cause permanent damage. Treat opals as delicate gemstones, not everyday workwear.

Cleaning Your Opal

Clean with warm water and mild soap. Avoid harsh chemicals like bleach, ammonia, or chlorine. Light exposure to hand soap or dishwashing detergent is safe.

Storage

Store opal jewelry separately from harder gemstones (diamonds, sapphires) to prevent scratching.

Solid Natural Opals

(Black, Boulder, Crystal, White Opal)
Natural solid opals are stable and won't change color or crack from water, humidity, or temperature changes. They are safe to submerge in water and can be worn daily, provided they are protected from physical impact. Solid opals are a single piece of gemstone with no artificial backing, making them ideal for heirloom quality jewelry when handled with care.

Opal Doublets

Opal doublets consist of a thin slice of natural opal bonded to a dark backing. Do not submerge doublets in water as prolonged exposure can weaken the adhesive bond and cause separation or cloudiness. Remove doublet jewelry before swimming, bathing, or washing dishes. Clean with a damp cloth only; do not soak or use ultrasonic cleaners.

Like all opals, doublets are fragile and must be protected from impact.

Not sure which type you have? Solid opals show natural color throughout the stone. Doublets have a visible dark backing layer when viewed from the side.

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Boulder Opal 12.18ct Blue Green Fire

AU$961

In stock

Details

Dimension:

26.5x14x4 mm

Weight:

12.18 ct

Type:

Natural Solid Untreated Boulder Opal

Source:

Winton, QLD, Australia

Sku:

XX1176

This 12.18ct natural Australian boulder opal from Winton, Queensland displays blue and green fire concentrated within a defined central color bar, surrounded by a softer light blue host. The freeform polished cabochon highlights natural contrast between the vivid color zone and surrounding ironstone.

About Boulder Opal

Boulder opal forms within ironstone, creating natural patterns where vibrant opal color contrasts with the host rock. Stones with defined color bars are valued for their natural structure and visual contrast.

Jewelry Use

This opal is suited as a loose gemstone for custom ring or pendant settings. The elongated freeform shape allows flexibility in design while maintaining strong visual focus on the central color.

October Birthstone

Boulder opal is part of the Australian opal family and is associated with October birthstone jewelry. Each stone displays natural variation in color and pattern.

Authenticity

100% natural solid Australian opal. No treatments. No doublets or triplets.


Learn more

Boulder Opal from Winton | What Makes an Opal Valuable| Australian Opal Buying Guide

Browse all Boulder Opal collection or contact us with questions.

Shipping Updates - March 2026

Latest international delivery information from Australia Post and FedEx.

USA Tariffย 

USA customers do not need to pay any tariffs on their purchase. Opal Galaxy covers all tariff charges to the USA, with no additional government fees added after checkout.

Delivery Status

USA: No delays
Asia: No delays
UK: Minor delays possible (Complimentary EMS Express upgrade)
Europe: Minor delays possible (Complimentary EMS Express upgrade)
Middle East: Shipping temporarily suspended - Please contact us to discuss shipping arrangements before purchase.

Shipping Information

All shipping includes complimentary insurance.

Registered Shipping $15 under $200
Free Registered Shipping over $201
Free Worldwide EMS Express Shipping over $1000
Free Worldwide FedEx Shipping over $4000
Extra Cost $25 EMS Shipping Upgrade under $200
Extra Cost $10 EMS Shipping Upgrade under $999
Extra Cost $100 FedEx Shipping Upgrade under $3999

Please view ourย Shipping Policyย page for more information.

7 day return and refund policy.
Please view ourย Return and Refundย page for more information.

We offer a lifetime guarantee for natural cracks that may form in our opals. There is a very low chance that this can happen, however occasionally it might. Our guarantee excludes any opals sold with existing fractures.
Please view our Terms and Conditions.

Caring for Your Australian Opal

Opal Jewelry

Important: Opals Are Fragile Gemstones
Opals are softer than sapphires, rubies, or diamonds and will crack or chip if struck hard against solid surfaces.

Always remove opal jewelry before:
Sports or physical activities
Manual labor, gardening, or gym workouts
Household tasks where impact is possible (lifting, moving furniture, etc.)

Even a minor knock during everyday wear can cause permanent damage. Treat opals as delicate gemstones, not everyday workwear.

Cleaning Your Opal

Clean with warm water and mild soap. Avoid harsh chemicals like bleach, ammonia, or chlorine. Light exposure to hand soap or dishwashing detergent is safe.

Storage

Store opal jewelry separately from harder gemstones (diamonds, sapphires) to prevent scratching.

Solid Natural Opals

(Black, Boulder, Crystal, White Opal)
Natural solid opals are stable and won't change color or crack from water, humidity, or temperature changes. They are safe to submerge in water and can be worn daily, provided they are protected from physical impact. Solid opals are a single piece of gemstone with no artificial backing, making them ideal for heirloom quality jewelry when handled with care.

Opal Doublets

Opal doublets consist of a thin slice of natural opal bonded to a dark backing. Do not submerge doublets in water as prolonged exposure can weaken the adhesive bond and cause separation or cloudiness. Remove doublet jewelry before swimming, bathing, or washing dishes. Clean with a damp cloth only; do not soak or use ultrasonic cleaners.

Like all opals, doublets are fragile and must be protected from impact.

Not sure which type you have? Solid opals show natural color throughout the stone. Doublets have a visible dark backing layer when viewed from the side.

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