This 3.7 carat neelam is a natural blue sapphire with Ceylon (Sri Lanka) given as the origin. Here is what to know and what to check when the parcel reaches you.

• Weight: 3.7 carats, priced at Rs. 21,380, which is about Rs. 5,778 per carat.
• Hardness: Mohs 9, so it can take a ring setting without worry.
• Reference: GS-000858, which is the number to give us when you write.
• Treatment: heating is common in sapphire; ask what we know about this stone before you commit.
• On arrival: open the parcel in front of the courier, look at the stone in daylight and against white paper, and compare it with the photographs.

Because Cash on Delivery lets you inspect before paying, you are never asked to trust the picture alone, and a stone of this weight is easy to judge properly once it is in your palm. If the stone is not what you expected, the return window is explained on the returns page. Other neelams for comparison are in the sapphire section.

Before you choose, read our sapphire guide.

This particular stone

This listing is one natural sapphire, known in Urdu as Neelam, with a weight of 3.7 Carat. Its price is Rs. 21,380 — roughly Rs. 5,778 for each carat. Origin: Ceylon (Sri Lanka). Treatment: treatment not tested. Quote reference GS-000858 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 sapphire 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 sapphire 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 sapphire 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): Most sapphire on the market is heated to improve colour and clarity; unheated stones exist and cost more. 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.