The Ultimate Guide to Opals: Color, Quality, Price, and More

The Ultimate Guide to Opals: Color, Quality, Price, and More

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The Ultimate Guide to Opals: Color, Quality, Price, and More

Hey everyone! Dominique here, for another deep dive into the world of gemstones. Today, we’re talking all about opals — one of the most mysterious and captivating gems out there and the October birthstone!

Opal Basics - What You Need to Know

Hardness: Is Opal a Soft Stone? 

lucky diamond horseshoe ring with opal and diamond

This particular gemstones has built a reputation of being a fragile or softer stone. We are here to debunk this myth, and want to highlight that this all comes down to the quality of the gemstone and how it is set. With a hardness of 5.5-5.6, they can be turned into a ring. When creating opal jewelry you intend to wear often, we recommend setting it in a bezel. This will help protect the stone from everyday wear and tear. 

An opal becomes fragile when it is thin. When you cut an opal you want to keep as much material as possible. We recommend using stones that are 2mm thick or more. If a stone is too thin, it can crack during the setting process, or there is a risk of breakage from everyday wear.

Cut: Cabochon vs. Faceted

Most of the time, opals are cut as cabochons because it is easier to see the opal’s optical phenomenon occur in this shape. Think of a cabochon as one large window looking into the stone.

In comparison to faceted stones, which often have many facets, lines, and corners, the appearance of color play and pattern can become muddied.

What Creates the Opal’s Color?

Fun Fact: Opal is not a crystal. Most gemstones (rubies, tourmaline, quartz, ect.) are crystals, so they have a crystallin system, meaning they have a specific axis and symmetry of how their atoms are arranged. Opal are amorphous, meaning their atoms are not organized like they would be in crystals (see image below). 

chrystalline and amorphous opal
Because of this disorganized structure, it creates the different variations of patterns, for example little pin points of color (left image) or big patches (right image), like a paintbrush stroke. 

blue opalblack opal with red flare

The beads that form an opal are composed of silica. When light passes through them, colors appear. The smaller the spheres, the less light passes through, meaning only shorter wavelengths can be seen. These shorter wavelengths produce green and blue colors. Larger spheres allow longer wavelengths to pass, which is when we see orange and red.

It takes longer for larger silica beads to form, which is why they are rarer. As a result, opals that display reds and oranges are the most desired and valuable.




Types of Opal and Their Characteristics

When the play-of-color is present, it’s called precious opal. Without it, it’s classified as common opal. To be considered an opal there needs to be no "host rock" within the stone. Host rock is traces of rock mixed into the composition of the opal. If it contains host rock it is no longer an opal but a boulder opal.

1. Black Opal (Most Expensive)

Starting with the rarest, black opals are the most expensive on the market. I've seen small black opals fetch prices of up to $15,000 due to their beautiful patterns and range of colors.

The base, or body color, can vary from dark gray to black, and it will be full opal (no host rock) throughout. Black opals are primarily found in Australia, though some with a dark body tone occasionally come from Ethiopia. However, Ethiopian black opals are not as commonly seen on the market.

Something to note: if you see red in the opal, expect a price premium—often three times higher—compared to stones that only show blue, green, or some yellow. As soon as you get yellow, orange, or red, the price jumps because these colors take the longest to form, making them much rarer.

Within black opals, small pinpoint specks of color are the most common and are considered less desirable by collectors. Higher-priced stones tend to feature paint-stroke-like patterns, often referred to as harlequin, Chinese writing, or ribbon patterns.

Australian black opal
  • Origin: Primarily Australia but can also be found in Ethiopia 

  • Body tone: Dark gray to black

  • Features: Bright flashes of red, orange, green, and blue. Red being the most desired color.

  • Price: $2,000–$15,000+ depending on size, pattern, and color

  • Collector's favorite due to rarity and vibrant color contrast

2. White Opal

White opals I would also recommend Australian origin, just because they're more durable. Ethiopian opal has been shown to go yellow over time. If you buy from a vendor, make sure the stone is 3 years or older to minimize the risk of the stone changing color. 

White opal uses the same principle of light refraction, but since it has a white base, its appearance is softer and less dramatic than that of black opal. This is why it is more commonly seen in jewelry—it is easier to wear than its darker counterpart, which is more often purchased by collectors.

Compared to black opal, white opal is a much more affordable option. A black opal and a white opal of the same size can differ in price by several thousand dollars.

white opal cabochon
  • More affordable than black opals

  • Body tone: White to translucent 

  • Softer, pastel color play

  • Recommend buying Australian white opals for better durability

  • Price: $200–$5,000+

 

3. Boulder Opal

Boulder opal is opal that has host rock inside the stone. It is commonly sand or ironstone from where the opal vein was mined from. Having host rock mixed into the stone can add durability.

boulder opal
  • Found in ironstone host rock

  • Typically cut with the matrix intact, making them more durable

  • Often used in large statement pieces like pendants or brooches

  • Price: $130–$4,000 depending on quality and size

  • Sold by the piece, not per carat

 

5. Fire Opal

Mexican fire opal is known for its striking, vibrant orange to yellow colors. While it can display color play, this effect is often harder to detect in orange and red stones, as the base color makes it difficult to distinguish. Greens and blues are more commonly seen.

It’s a great alternative to spessartite garnet, as it is one of the few gemstones that display such beautiful shades of orange.

Mexican fire opal

 

  • Body color ranges from yellow to orange to deep red

  • Some specimens display color play, though it can be subtle

  • Often translucent to transparent

  • Origin: Mexico and Brazil

  • Price: $1,000–$5K+ depending on size and clarity

6. Common Opal

Common opal is any opal that does not display any color play. This makes them semi-precious. They come in unique pastel pinks, turquoise greens and even blues. More commonly found as opaque colors, we can also find more translucent colors.

common opal pink
  • No play-of-color

  • Available in a range of pastel colors (blue, pink, neon green)

  • Often mistaken for chalcedony

  • Affordable and great for casual, colorful jewelry

 


 

Setting & Wearability Tips

One of the most frequently asked questions is whether you can wear opal as an engagement ring. The answer is yes! Although opal is a softer stone, there are ways to protect it from damage. We recommend setting the stones low and close to the finger, preferably within a bezel setting. You can also have them encased by diamonds, such as in a halo. These methods all help reduce the risk of damaging your stone.

custom opal ring with diamonds and 14k gold
  • Opals rank 5.5–6.5 on the Mohs hardness scale, so they’re relatively soft.

  • Best used in pendants, earrings, or protected ring settings (like bezels).

  • A thicker opal is safer to set. Paper-thin opals can crack during setting or everyday wear.

  • Cabochon cuts are common to enhance color play, though opals can be faceted for a unique look.

 


 

Opal Price Guide (Examples)

Type

Size

Price Range

Matrix Opal

Small (~10–15 mm)

$130–$300

Boulder Opal

Medium–Large

$130–$4,000

White Opal

8–15 mm

$500–$1,000+

Fire Opal

1.5–3 carats

$1,000–$1,500

Black Opal

Small to large

$2,000–$15,000+

Pro Tip: Red and orange flashes in opal significantly increase the price due to rarity.

 


 

Coming Up: Opal Care, Treatments & Synthetics

 

men's stone inlay ring with cremation remains

 

We're breaking this topic into two parts! In our next post and video, we’ll cover:

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Want to Buy or Design with Opal?

Australian black opal blue shimmer

If you’re looking to create a custom engagement ring or want help sourcing high-quality opals, feel free to reach out via the links below. We specialize in natural gemstones and custom jewelry.

Have questions or want to share your opal stories? Drop a comment below!

— Dominique Flux

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