As with any precious gem, the value of Australian Opal will vary, based on several factors. Similar to Diamonds, Opals are valued on carat weight, colour, clarity, and brightness, with the addition of rarity (opal type), and pattern. This blog will reveal 9 ways to know how much an Australian opal is worth.

Opal has been symbolic of Australia for over a century (even becoming the national gemstone in 1995), and is regarded as one of the ‘big six’ of gemstones (others being diamond, emerald, ruby, sapphire and pearl), and there are many ways to understand this gem’s value and true worth.

Australian Opal values can increase dramatically in price if the demand for a particular type goes up, so always keep an eye on what type of Australian Opal is trending and favoured.

Let’s have a look at the main factors that determine an Australian opal’s value.

1. Colour

Opals are known for their array of colours, often showing all the hues of the rainbow. But did you know that certain colours are more valuable than others? Purple is the most commonly formed colour, and generally has little value. Blue is the first colour to truly show any kind of value and is often known as the ‘colour of Opal’ to most. Green hues will see the price increase, but it is when we get to the orange, pink and, most notably red tones that the price will rise, often considerably. When red appears in the darker Opals (Black and Boulder), this becomes a well sort-after combination. The colours in Australian Opal occur thanks to the diffraction of white light into the colour spectrum due to the chemical composition (hydrated silica) of natural opal.

2. Pattern

The patterns that appear naturally in Australian Opal are so unique, and random, but we are still able to group them into specific types, pending on their rarity. The most common patterns to occur are the Floral/ Pinfire and Grass types, with the Floral pattern showing a random mish mash of colours, looking like a garden bed, while the Grass pattern shows off wisps of colour. Broad and Rolling Flashes are larger patterns, with the latter acting like a cat’s eye type, with the colour ‘rolling’ over the opal. Flagstone patterns are a random, blocky type of pattern, while the rarest and most valuable pattern is the Harlequin – a natural checkerboard pattern that just dazzles. Other patterns include Chinese Writing, Mackerel, Pinfire, and combinations of all of the previously mentioned.

3. Clarity

This is to do with how ‘clear’ the gem is, that is, if there are any natural inclusions appearing. Inclusions can include sand spots, ironstone specks, natural potch (colourless Opal), and potch ‘webbing’, all of which, if occurring, can affect the overall value of the opal. When valuing Australian Opal, we are looking for a nice, clean face, with little to no inclusions, to make for a truly valuable gem. There can be a contradiction to this when the inclusion can actually help create a pattern (most notable the Flagstone pattern), where in that particular case, the inclusion will help to increase the value of the opal, not decrease it.

4. Brightness

This one is pretty straightforward. The brighter the Australian Opal, the higher its value. We rank our Australian Opals from subdued (dull), through to bright (having some indication of fire), and brilliant (very vibrant, with plenty of fire). Brilliant stones have little to no help from natural light to really show off their colour. There is a rating from 0 to 5, with 0 being the dullest, and 5 being the most brilliant in Australian Opal.

5. Body tone

Australian Opals are so varied, and certain types carry a particular ranking in the body tone chart, ranked from N1 for the most intense dark body tone, through to N9 for the milkiest/lightest body tone. Generally speaking, Black Opals will rank from N1 to N4, with Semi Black Opals ranking from N5 to N6. Crystal Opals cover N7 to N8, and White (or Milky) Opal hitting N9 in the Body Tone chart. Boulder Opals receive an N0 ranking (thanks to their natural ironstone backing), but are comparable to N1 to N6 rankings.

N1s are considered to have the highest value, due to their ability to really push intense colour, whereas N9s are the most common, and lowest in value.

6. Origin (or Rarity)

Australian Opals are found in different areas, with certain Australian opal fields yielding more than others. White or Milky Opals (Coober Pedy, South Australia) are considered the most common of the precious opal, followed by the translucent Crystal Opals (South Australian fields, Lightning Ridge NSW, and White Cliffs NSW). Gem-grade Boulder Opal from the Queensland fields are considered the second rarest, and the Black Opal from Lightning Ridge being the rarest, and most sort after of the gem-grade Opals in Australia.

7. Natural or treated

Solid Australian gem-grade Opal will be natural, and will not be heat treated. The addition of heat to Australian Opal would actually cause crazing or fracturing. There are, however, certain types of Matrix Opal that are stabilised and enhanced, these being Andamooka Matrix Opal (which is cooked in sulphuric acid, then soaked in a sugar solution to darken, enhance, and stabilise), and Fairy Opal from Winton (Queensland), which is darkened and hardened using a patented Carbonisation method.

All Solid Natural Australian Opals listed at Opals Down Under have not been treated (unless they are of the Andamooka Matrix or Fairy Opal variants, which we hardly stock). Do keep in mind, that the other form of ‘enhancing’ is the use of Triplet or Doublet Opals, which use a sliver of light Australian opal (usually Crystal Opal), adhered to a dark backing to give the appearance of Black or Boulder Opal, and in the case of Triplets, a Synthetic resin capping. These are clearly marked on the website and in-store.

8. Carat

Gemstones are valued on their size, which is known as Carat weight. One carat is equivalent to 1/5th of a gram. The price per carat for Australian Opals is dictated by the before-mentioned factors, all of which will increase or decrease the value of the stone.

We’re here to help

Opals Down Under is a fantastic place to check an Australian Opal’s value. Our staff and Opal Artisan/Director have a multitude of experience in dealing with Australian Opals and can assist in explaining your opal’s value, and or identify the stone for you.

All our products are supported with excellent customer service and authenticity to ensure your purchase is a worthwhile experience. We will help you find exactly what you are looking for. Contact us today to see which Australian opal would suit you best.