A star-like reflection that shifts across the surface as the stone or the light moves: that is asterism, and it is what makes this 23.70 carat African purple sapphire notable, rather than a crisp faceted sparkle.

It also shows how a large weight dilutes the rate per carat. A stone half this size from the same family would not cost half as much, and one twice the size would not cost double, which is why a per-carat figure only means something when you compare stones of similar quality.

Sapphire is among the hardest natural stones, 9 on the Mohs scale, so the surface keeps its look through everyday wear.

Treatment and what to ask

Purple sapphire often gets a heating pass to settle its colour, and untouched stones are rarer. Ask us what we know about this exact piece (reference AG-000507). If you want written confirmation, independent lab testing is your option.

A stone of this weight wants a bold setting: a pendant or a chunky ring. Other sizes are in the purple sapphire collection.

We send it by insured, tracked courier with Cash on Delivery, so you see the stone before any money changes hands. Karachi is usually 1–2 working days, other cities 2–4, and returns are accepted within 7 days. Our purple sapphire guide has more.

This particular stone

This listing is one natural purple sapphire with a weight of 23.7 Carat. Its price is Rs. 8,890 — roughly Rs. 375 for each carat. Origin: Africa. Treatment: treatment not tested. Quote reference AG-000507 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 purple 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 purple 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 purple sapphire 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): Purple sapphire is often heated to refine its colour; unheated stones are less common. 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.