1. Identify the Type of Opal
Black Opal: Considered the most valuable, black opals have a dark body tone, which makes the colours more vivid. They are primarily mined in Lightning Ridge, New South Wales.
Boulder Opal: These opals are naturally attached to the host rock, which gives them unique patterns and colours. They are often found in Queensland.
White or Light Opal: Known for a light or milky body tone, white opals display colours in a more subtle way. They are commonly found in Coober Pedy, South Australia.
Crystal Opal: Known for its transparency or translucency, allowing colours to shine from within. Crystal opals can be found in several regions.
Doublets and Triplets: These are opal composites where a thin slice of opal is backed (or also topped in triplets) with another material. Always make sure you purchase a solid opal. Doublets and triplets at time
2. Assess the Play-of-Colour
Opals display flashes of colour due to diffraction of light. Look for opals with vibrant, varied colours that shift as the stone moves.
Red flashes are often more valuable than green or blue, although personal preference plays a role.
3. Evaluate the Body Tone
Darker body tones, like those in black opals, are usually more valuable due to the higher contrast in colour. Body tone is graded from N1 (black) to N9 (white), with darker tones typically more desirable.
4. Check the Clarity
Clarity in opals means they are free from cloudiness or imperfections that can obscure colour. Some types, like boulder opals, naturally have visible host rock inclusions.
5. Understand the Cut and Shape
Australian opals are typically cut in cabochon shapes (domed, smooth tops). A well-cut opal should have a symmetrical shape and an even surface to showcase its colours optimally.
6. Consider Your Budget and Source
Genuine Australian opals can be pricey, especially black opals and boulder opals. If buying online, make sure the vendor is reputable and provides detailed images, as opals look different from various angles.
7. Purchase Certified Opals
If possible, buy opals with a certificate of authenticity to ensure you are getting a natural, untreated stone from an Australian mine.
Taking time to view different opals, especially in natural light, can help you find a piece that truly appeals to your tastes and budget.
