How To Value Opal - The 10 Factors

How To Value Opal - The 10 FactorsOn a scale of one to ten Opal is easily the hardest gemstone to try and value. Opal has an infinite number of variables including color, pattern, brightness and origin. Opal has a complicated classification system for valuations that is much harder than diamonds or any other gemstones.

If you are ready to take the plunge and purchase your first Opal or if you are an avid collector, this article is going to walk you through the 10 factors that contribute to the final price of an Opal.

Given that there are 10 separate factors that con contribute tot he final price of an Opal, there is a certain degree of movement in pricing. Many Opal miners can under or over value their opals when it relates to supply and demand and what market they are selling to. Many buyers on Opal Auctions use our ITEM WATCH to track what Opals sell for.

Over many years there has been guidelines developed on how to value Opal. We are going to explore the 10 factors that contribute to an Opals final value. These factors are:

  1. Color
  2. Direction / Play Of Color
  3. Pattern
  4. Body tone
  5. Brightness
  6. Shape
  7. Inclusions
  8. Which Opal Field
  9. Natural vs Treated
  10. Country Origin

How Opal Is Valued In Lightning Ridge, Australia

At Lightning Ridge in Australia, they have a committee that values opal miner’s opals each Saturday. Several experienced opal valuers will price the opal per carat and the final value will be determined by the average price per carat. The above factors can vary from person to person and that is the reason you may see variation in price per carat amongst miners.

During this article if you are not sure of any of the terms, checkout our glossary for an explanation on just about everything spoken in the Opal world.


Color is the first thing that you will notice about an opal. Red is the rarest and most sought out color. In order of value, the most valuable color is red, then orange, green, blue and purple. However, Opal is usually never a single color. It is important to decide what the dominant color is followed by any secondary colors. Use the dominant color as the color that will affect the price.

Some Opals of note would be the red Opal with a purple hue color bar hidden inside. This will create a deep majestic red color. Also electric blue Opals are more valuable as the hidden color bar makes the Opal brighter than the normal blue.

Density and intensity of color is also important to determine the price. The thickness of the color bar can help to amplify the brilliance of the Opal color. Seam Opal generally has a thinner color bar than opals formed in a knobby.

How To Value Opal - The 10 Factors Guide  Opal Auctions


Opals are a gemstone that dramatically change appearance based on what angle the Opal is viewed at. When an Opal is at it’s brightest, this is called ‘facing’. The direction of color can affect the price becuase it will determine how versatile the Opal is. If it only faces in one direction, it may only be suitable for a Pendant for example.

  • Opals that face with strong fire from all directions make good ring stones. These Opals are very versatile and are more valuable than one directional opal. A fine quality Opal will look good no matter what direction it is viewed at.
  • An opal that faces in one direction is ideal to make into a pendant. The jeweler will set it in the right direction so as to show as much of the fire as possible.
  • Some multi-color opals might have 1 or 2 strong colors that have different directional faces and these can be hard for jeweller to set. 
  • Dead spots are when no color is visible from a certain angle. These will lower the overall value of the Opal.


Opals that have a rare or unique pattern are more valuable. The Harlequin pattern is the rarest and most loved pattern in opals but it is very rare. A True harlequin pattern is a mosaic broad pattern, angular close set of colors. Floral patterns are sometimes called floral harlequin.

Some top patterns are Mackerel, Block, Broad flash, Rolling flash, Pinfire, Rainbow and most sought out Ethiopian opal is the Honeycomb pattern. Opals that have no or only slight pattern are generally less valuable.

How To Value Opal - Pattern - Mackerel Pattern Opal


The Opal Body Tone Guide was endorsed by the Opal Association of Australia and was intended to be a guide for Black Opal and Boulder Opals. It is now generally excepted for all opals worldwide. Opals are grouped in 9 sub categories N1 to N9 with N1 the darkest opal and N9 the lightest.

  • Black opals are generally the most valuable and have a body tone of N1 to N4 
  • Opals with N5 to N6 considered a semi black or dark opal. 
  • Body tone N7 to N9 are called crystal opals.

How to value opal - the base body tone chart


The Opal brightness guide was produced by the Australian opal association along with the body tone guide. There are 7 sub Brightness ratings with B1 the brightest to B7 the dullest. The brighter the Opal, the more expensive will be its value. How to value opal - the brightness chart


Oval stone are generally considered more valuable than free form, except with boulder opals where free form is considered desirable. The shape of the Opal once again determines how versatile it is. Oval stones generally have the best face of color and can be used in a variety of applications.

Opal is almost always cut in a cabochon. A cabochon stone is more valuable when it has a high dome compared to a a flat stone. This is due to the fact that cabochons make ideal ring stones but flat stones are less desirable because they cannot be used in many jewelry designs.


Inclusions and potch lines and are not to be confused with cracks. A crack line reflects light and greatly devalues an Opal. It is worth reading about the difference between crazing and cracking in an Opal.

A potch line has no light reflection and these opals are generally valued lower but can make artistic picture patterns. 

Some Opals will have a vegetation pattern from the inclusions and this is popular as the opal has replaced some of the tree or vegetation. Sand or windows also reduce the value of the opal. A window is a gap on the bottom where potch has not formed and opal is transparent.

Ethiopian opal can have a ghost or phantom inclusions or vegetation matter. These types of inclusions are generally accepted as reasonable in this type opal. How To Value Opal - Inclusions


The end buyer or wholesaler might not be able to consider this factor. But in the trade certain mines have a reputation of producing good quality rough that makes excellent stones. This happens in Australian and Ethiopian opal fields. Even the depth of the mine can greatly effect value.

In the trade, this can be an important factor for repeat buyers. If you find a seller has certain stocks that you like, it is best to purchase from that group. 


Natural Opal is always valued higher compared to treated Opal. Over the last few years smoked or treated Ethiopian crystal opal has been sold as natural Black Opal. This treatment is not permanent. Opal Auctions has sellers who must clearly state that the opal is treated. Unfortunately we now see lots of fake opals offered for sale, not only online but also spiced in parcels of rough opals. 

Fake Opal or synthetic Opal is also somethng to watch out for. It is best to educate yourself on how to spot a fake Opal.

Opal doublets and triplets do not have the same stringent criteria as solid opals and are valued considerable less. It is important to be able to pick a doublet opal compared to a solid and this can be difficult when the opal is set into jewelry. Checkout these resources:


Australia has a worldwide reputation as the world’s most expensive opals. Many countries now produce good opals like Ethiopia, Mexico and Brazil. Each country’s opals may be unique and this factor helps determine the Opal price.


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15 people found this article helpful



Excellent , information ,very helpful and much appreciated ,thank you.

7th Jul 2021

Very helpful indeed.

21st Jun 2020

I found it to be very interesting always go back to the basics basics her where it's at a beautiful baseball player that can't hit any more they take him back to the basics always love review in that

27th May 2020

Advice very helpful

16th Jun 2018


7th May 2018

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