Gem education
A buyer’s guide to Sri Lankan gemstones.
Everything you need to buy with confidence — what makes Ceylon gems special, how value is judged, treatments, certificates and how our auctions work.
The island of gems
Sri Lanka — historically known as Ceylon — has been a celebrated source of precious stones for more than two thousand years. Most of its gems come from gravel-rich alluvial deposits, with the Ratnapura district (literally “city of gems”) and the Elahera region among the best-known mining areas.
The island is famous for the variety of gem species found in a small area, and above all for its sapphires, which are prized for their bright, lively colour.
Signature gemstones
Blue Sapphire
Ceylon blue sapphires are known for bright, luminous tones — from soft cornflower to deep royal blue — with excellent brilliance.
Padparadscha
A rare sapphire in a delicate blend of pink and orange. The name comes from the Sinhala word for the lotus blossom.
Pink & Fancy Sapphires
Sapphire occurs in pink, yellow, purple, white and more — often called “fancy” sapphires.
Cat's Eye
Chrysoberyl showing a sharp band of light (chatoyancy) that glides across the dome of the stone.
Alexandrite
A colour-change chrysoberyl — typically greenish in daylight and reddish to purplish under warm incandescent light.
Spinel
A durable, brilliant gem in reds, pinks and purples, increasingly valued by collectors.
Ruby
Red corundum — the sister of sapphire. Sri Lankan rubies often show a lighter, bright raspberry tone.
Moonstone
Feldspar with a floating blue-white sheen (adularescence), long associated with Sri Lanka.
How value is judged
The most important factor for coloured gems: hue, tone (lightness) and saturation. Vivid, evenly distributed colour is most valued.
Most natural coloured gems contain inclusions. “Eye clean” stones show none to the naked eye; some inclusions help identify natural origin.
A good cut maximises brilliance and colour, with even proportions and minimal dark areas (“extinction”).
Weight — 1 carat = 0.2 g. Prices per carat usually rise sharply for larger fine stones.
Treatments & disclosure
Many gemstones are treated to improve colour or clarity. Traditional heat treatment of sapphires is widespread and generally accepted when disclosed; untreated (“unheated”) stones of comparable quality are rarer and usually command a premium. Other treatments — such as diffusion or fracture filling — have a much larger effect on value.
On Lessel Ceylon Gem every listing states whether the stone is natural or laboratory-grown and its treatment status. Sellers must disclose all known treatments.
Certificates
An independent gemmological report identifies the stone, confirms whether it is natural, and states detectable treatments — and for some stones, geographic origin. In Sri Lanka, the National Gem & Jewellery Authority (NGJA) provides testing; internationally recognised laboratories include GIA, Gübelin, SSEF, GRS and AGL, among others.
Look for the Certified badge and open the certificate on each listing. Always check that the report number, weight and dimensions match the stone.
Buying at auction
- Create a free account and confirm your email address.
- Study the photos, video, specifications and certificate — ask us anything before you bid.
- Enter a bid of at least the minimum shown. Bids are binding.
- Bids placed in the final 2 minutes extend the auction, so everyone has a fair chance to respond.
- If yours is the highest bid when the timer ends (and any reserve is met), you win — we email you payment and insured delivery details.
For gem dealers, miners & collectors
Reach international buyers with every stone.
Apply for a verified seller account, list with photos, video and certificates, and sell at a fixed price or at auction — we handle marketing, buyers and transactions.