Dur-e-Najaf is not a mineral name. The mineral is quartz — silicon dioxide, the same species as amethyst, citrine and rock crystal — and "Dur-e-Najaf" is the name given to the white to colourless variety traditionally worn in silver rings. Knowing that is the single most useful thing a buyer can know, because it tells you what to expect from the stone and roughly what it should cost.

The stone

77.55 carats, which is 85.22 ratti. Rs. 6,380, about Rs. 82 per carat — the lowest per-carat rate in our Dur-e-Najaf range. Reference GS-000218. Recorded shape: oval. Recorded colour: colourless.

What "crystal quartz" means in practice

• Hardness 7 on the Mohs scale. Harder than window glass and most household dust, which is why quartz jewellery survives daily wear.
• No cleavage. Quartz does not split along planes the way topaz or fluorite does, so it takes a knock better than its hardness alone suggests.
• Chemically dull, in a good way. It does not react to sweat, soap or perfume.
• Common, and honestly priced because of it. Quartz is one of the most abundant minerals on earth. A Najafi stone should cost tens to a few hundred rupees per carat, not thousands.

Why this one is the cheapest per carat

Size. Across our collection the per-carat rate falls steadily as stones get bigger — from around Rs. 492 on the smallest piece down to Rs. 82 here. That is the opposite of what happens with rare gems, where big stones command a premium, and it is exactly what you would expect from an abundant mineral: there is no scarcity to pay for, so a large stone simply spreads its cost over more carats.

What it looks like

Milky white and evenly coloured. We measured the photograph instead of describing it from impression: the red, green and blue values sit within a few points of each other, so the white is genuinely neutral. The brightness variation across the stone measures 8, where a faceted see-through gem photographed the same way measures around 65. It is a translucent cabochon — light goes into it and glows, but it is translucent rather than transparent. That soft internal light is the character of the stone and the reason it is cut as a dome rather than faceted.

Treatment

Dur-e-Najaf is clear quartz and is usually untreated. There is no heating, dyeing, irradiation or filling involved in this type of material, and none is recorded for this stone. That is one of the quieter advantages of buying quartz: with most coloured gems you have to ask what has been done to them, and here the honest answer is usually nothing.

Telling it from the imitations

Glass and plastic are the two things sold in its place. Glass gives itself away by warmth — quartz feels cold against the lip for noticeably longer — and by rounded bubbles under a loupe, which natural quartz does not have. Our real or fake guide runs through the checks, the general guide to real and fake stones covers the wider problem, and our authenticity page explains what we do and do not certify.

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 dur-e-najaf with a weight of 77.55 Carat. Its price is Rs. 6,380 — roughly Rs. 82 for each carat. Treatment: treatment not tested. Quote reference GS-000218 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.

Above twelve carats you are into collector territory. Pieces this heavy are usually set as pendants or kept loose, and they are prized for the size of rough they came from. If you do set it, choose a bezel or a heavy claw to protect the edges.

On the Mohs scale dur-e-najaf rates 7. It handles daily wear, but a hard knock can still nick an exposed corner, so a protective setting is a sensible choice. Clean it with warm soapy water and a soft brush, and keep it away from abrasive cleaners and high heat.

Whoever you buy dur-e-najaf 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 dur-e-najaf 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): Dur-e-Najaf (clear quartz) is usually untreated. 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.