A 5.2 carat precious opal — 5.71 ratti — at Rs. 12,750, about Rs. 2,452 per carat.

Precious opal, and what the word actually means

It is not a grade or a compliment. Precious opal is the half of the species that shows play-of-colour; common opal, or potch, is the half that does not, however attractive its body colour may be. The difference is structural. In precious opal the microscopic silica spheres are uniform in size and stacked in an orderly grid, which diffracts light into spectral flashes. In common opal the spheres are irregular, and no amount of polishing will produce colour that the structure cannot make.

This stone is unambiguously precious opal: play-of-colour covers 8% of its face, spread across nine distinct hue bands. That spread is what you are paying for.

A correction worth making plainly

This stone was previously listed as a black fire opal with a dark body. It is neither. Its body tone measures 199 out of 255, among the lightest grades there are, with no dark regions anywhere on the stone. Black opal has a dark grey to black body and is one of the most valuable gems in the world; fire opal is a transparent orange-to-red material that shows little or no play-of-colour. This is a white-body precious opal, which is a good thing to be and is described correctly here.

Body tone is graded separately from colour

The two things are judged independently, and both matter. Body tone runs on a scale from N1, jet black, to N9, white. A dark body makes play-of-colour appear more intense by contrast, which is why black opal commands the prices it does. A light body gives a softer, more pastel display. Neither is a fault; they are different materials at different prices.

Care

Opal is 5.5 to 6.5 on the Mohs scale and holds water in its structure. No ultrasonic cleaner, no steam, no sudden heat. A soft damp cloth is the whole routine. Keep it away from harder stones in storage and take any ring off before household chemicals.

Treatment has not been tested on this stone, which we record rather than describing it as untreated. No documented origin is held for it. Dimensions and clarity are not recorded yet; ask and we will measure.

This particular stone

This listing is one natural opal with a weight of 5.2 Carat. Its price is Rs. 12,750 — roughly Rs. 2,452 for each carat. Treatment: treatment not tested. Quote reference GS-000733 when you message us about it. The photographs show this exact stone, so what arrives at your door is the piece you chose on screen.

Between two and six carats is the range most people choose for a gents' ring or a noticeable pendant. Here colour drives the price more than size does, which is why two stones of near-identical weight can be priced very differently.

On the Mohs scale opal rates 5.5 to 6.5. That is middle-of-the-road hardness: comfortable in pendants and earrings, and in rings worn with some care. Store it apart from harder stones so it does not pick up scratches, and wipe it with a damp cloth rather than scrubbing.

Whoever you buy opal from, make sure of three things: the stone is natural rather than lab-grown, glass or glass-filled; any treatment is stated in writing; and the weight quoted is the weight of the finished stone. We check every opal for those three points before it is listed, a certificate is available on request, and because you pay on delivery you can look at the stone — or have it tested — before any money changes hands.

We sell natural stones only and inspect each one before it is listed. Treatment for this stone: Treatment not tested. Certificate available on request. As general background (not a statement about this stone): Solid opal is usually untreated; some opal is smoke- or sugar-treated, and doublets/triplets exist — we sell solid natural opal. Ask us on WhatsApp and we will tell you what we know about this exact stone; independent lab testing is available on request.

A certificate of authenticity is available on request for this stone, and independent laboratory testing can be arranged. Because you pay on delivery, you can also take the stone to a lab of your choice within the 7-day return window. Read more on our authenticity page.