Afghanistan is the stated origin of this 5.15 carat ruby, and five carats is a stone worth checking carefully. Here is what to look at.

• Weight: 5.15 carats; a natural ruby, red in colour.
• Hardness: 9 on the Mohs scale, so it resists scratching in daily wear.
• Treatment: heating is common in ruby; ask us what is known about this stone.
• On arrival, tilt it in daylight and check that the colour matches the photographs.
• Look for glassy, flash-like patches inside, which can point to filling, and tell us at once if you see any.
• Quote AG-000559 on WhatsApp for questions.

Lower-grade ruby is sometimes glass-filled, and we do not sell such stones as natural ruby. Independent lab testing is your option, and you can do all these checks before paying. More stones for comparison are in the ruby collection, and the real versus fake gemstones guide covers general checks worth borrowing.

The parcel comes Cash on Delivery, so the stone is in your hand before you pay a rupee. Karachi: usually 1–2 working days. Elsewhere in Pakistan: usually 2–4. Returns: 7 days, unused and in its packing.

This particular stone

This listing is one natural ruby, known in Urdu as Yaqoot, with a weight of 5.15 Carat. Its price is Rs. 18,000 — roughly Rs. 3,495 for each carat. Origin: Afghanistan. Treatment: treatment not tested. Quote reference AG-000559 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 ruby rates 9. Few materials will scratch it, so it copes well with everyday ring wear. A soak in warm water with a drop of mild soap and a soft brush keeps it bright; skip the ultrasonic cleaner if inclusions reach the surface.

Whoever you buy ruby 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 ruby for those three points before it is listed, 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. No lab report yet; independent testing welcome. As general background (not a statement about this stone): Most ruby (yaqoot) is heated, and lower grades may be glass-filled; we do not sell glass-filled ruby as natural ruby. 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.