Opal has been a favourite in women's jewellery for well over a century, and the reason is that it does something no faceted stone can. A sapphire gives you one colour from every angle. An opal changes as the hand moves — green, then orange, then blue — so the same piece reads differently through the day.

The stone

2.50 carats, which is 2.75 ratti. Shape: oval cabochon. Origin: Australia. Rs. 12,500, about Rs. 5,000 per carat, reference GS-000701.

Three ways to use a stone this size

• Pendant. The kindest home for an opal. A pendant takes a fraction of the knocks a ring does, and the stone hangs where daylight reaches it, which is where play-of-colour works best.
• Dress ring. Lovely, and perfectly practical with a bezel setting and a little care — see below.
• Earrings, if you can match a pair. Matching opal for colour and pattern is genuinely difficult, so tell us early and we will look through the parcel rather than promise.

Which metal

925 silver and white gold keep the focus on the colour and suit the cool greens and blues. Yellow gold warms the stone and flatters orange fire. Rose gold is a harder match. Because opal is a cabochon with a domed top, a simple bezel in any of these looks right — the metal frames the colour rather than competing with it.

Is opal unlucky?

It is worth answering, because somebody always mentions it. The superstition traces to a nineteenth-century novel, not to any older tradition, and it was reportedly encouraged by dealers in competing stones. Opal is October's birthstone and has been worn as a stone of clear sight and imagination for far longer than the superstition has existed. We pass that on as tradition, not as a promise about outcomes. Our October birthstone guide has the background.

Caring for it

Opal is 5.5 to 6.5 on the Mohs scale — the softest gem we sell — and it holds water in its structure. Clean it with a soft damp cloth only. Never use an ultrasonic or steam cleaner. Put it on after perfume and hairspray, not before. Keep it out of prolonged direct sun and very dry heat, which can cause the fine surface cracks called crazing. Store it away from harder stones so nothing scratches the dome.

Solid opal and treatment

We sell solid natural opal, not doublets or triplets; the side profile of any opal shows which it is. Solid opal is usually untreated, though some is smoke- or sugar-treated to darken the background, and this stone has not been tested — our specification says so rather than claiming otherwise. A certificate of authenticity is available on request.

Ordering

One piece only. Flat Rs. 500 delivery anywhere in Pakistan, insured and tracked, dispatched in one to two working days. Cash on Delivery, seven days to return it unused. Measurements on request — WhatsApp +92 308 887 3888. More in the Australian opal collection.

This particular stone

This listing is one natural australian opal with a weight of 2.5 Carat. Its price is Rs. 12,500 — roughly Rs. 5,000 for each carat. Origin: Australia. Treatment: treatment not tested. Quote reference GS-000701 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.

Whoever you buy australian 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 australian 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.