"Rainbow" gets attached to a lot of opals that show one colour and a hint of a second. So rather than take the word on trust, we measured it. Every Ethiopian opal in our stock was sampled across the centre of the stone and its colour flashes sorted into hue bands. This stone is the only one that registered three distinct bands rather than two — greens, oranges and reds all present strongly enough to count.

The stone

1.50 carats, which is 1.65 ratti. Rs. 3,750, Rs. 2,500 per carat, reference GS-000729. Recorded shape: oval. Origin: Ethiopia. One piece, as photographed.

What play of colour actually is

It is not a pigment. Opal is built from microscopic spheres of silica packed in a regular grid, and when those spheres are about the size of a wavelength of visible light, the grid diffracts light into spectral colours. Which colours you see depends on how big the spheres are and which way the stone is tilted — which is why opal changes as it moves and a photograph can only ever show one moment of it.

On this stone, colour flashes cover about 11% of the face, against a body measuring 200 out of 255 in brightness — a bright, light background that lets the colours sit clearly on top rather than getting lost. At 1.50 carats this is a small stone, which is why the rate per carat is higher than on our larger pieces: the colour is concentrated into less material.

Judging play of colour yourself

1. Coverage. What share of the face lights up, rather than how bright one patch is.
2. Range. How many distinct colours appear. Red is the scarcest and lifts the price most.
3. Directionality. Tilt the stone. Colour that survives from several angles is worth more than colour that appears from exactly one.
4. Pattern. Broad, organised flashes read better than a fine scattered speckle.

The water question

Ethiopian opal is usually hydrophane and absorbs water. A wet stone can turn clear or cloudy and lose its play of colour temporarily; it returns as the stone dries. Dry it slowly at room temperature, never with heat, and keep it away from oil and perfume, which soak in and stay. Take it off before washing, swimming or wudu.

Treatment

Not tested, and the specification sheet says so. The treatment worth knowing about is smoke treatment, which darkens a pale body to mimic scarcer dark-bodied material; nothing about this bright stone suggests it, but we have not run the test. Independent laboratory testing can be arranged on request.

Care

Opal rates 5.5 to 6.5 on the Mohs scale. Protective setting, soft dry cloth, no ultrasonic cleaner and no steam. Look for crazing — fine surface cracks — under a light before you commit to any opal.

More

The opal buying guide goes further into judging colour, the Ethiopian opal price guide explains the rates, and the collection page has the rest of the stones.

Ordering

One piece only. Flat Rs. 500 delivery anywhere in Pakistan by insured, tracked courier, dispatched in one to two working days. Cash on Delivery — open the parcel and look at the stone before you pay — and seven days to return it unused. Dimensions have not been recorded; message us on WhatsApp at +92 308 887 3888 and we will measure it.

This particular stone

This listing is one natural ethiopian opal with a weight of 1.5 Carat. Its price is Rs. 3,750 — roughly Rs. 2,500 for each carat. Origin: Ethiopia. Treatment: treatment not tested. Quote reference GS-000729 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.

Under two carats, a stone like this sits neatly in a slim ring, a stud or a delicate pendant and does not snag on sleeves. It is also where many first-time buyers begin when a stone is recommended for astrological reasons, because the total cost stays modest.

Whoever you buy ethiopian 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 ethiopian 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.