Bangkok Silom & JTC
The world's coloured-stone trading floor — Bangkok's Silom, where the bulk of the world's rubies and sapphires are cut, treated, and traded
Coloured-stone trade
Silom, in Bangkok's Bang Rak district, is the world's coloured-stone trading floor — the densest concentration of gemstone dealers, cutters, and exporters anywhere, clustered around Silom and Mahesak Roads and anchored by the 59-storey Jewelry Trade Center.
The scale of Thailand's role is hard to overstate: by trade reckoning, around 90% of the world's rubies are cut and traded here, more than 80% of the world's coloured stones are processed in the country, and Thailand ranks as the world's second-largest exporter of corundum — the ruby-and-sapphire family.
Its defining edge is treatment. Thailand's mastery of the heat treatment of coloured stones is unrivalled, and it is what draws rough corundum from Myanmar, Sri Lanka, East Africa, and beyond to Bangkok to be transformed, certified, and traded onward. Stones arrive from across the world and leave through Silom.
It is a working trade district rather than a heritage quarter — dealer offices, cutting rooms, and labs stacked into towers. A caution for visitors: Bangkok is also notorious for gem scams aimed at tourists, so the real trade runs on established dealers and independent certification.
Planning to visit or buy in Bangkok Silom & JTC?
Getting there and when to go, what a fair price looks like, how to verify what you're buying, and how to spot a fake — the practical, no-nonsense guide.
Read the buyer's guideWorked here
A gemstone is rarely mined, cut, dealt and sold in the same place — those are four different trades. Here is Bangkok Silom & JTC's part in that journey: the stones it handles, and exactly what it does with each.
- Cut
- faceted, carved or finished here
- Treat
- heated, irradiated or enhanced here
- Trade
- dealt and wholesaled here
- RubyCutTreatTrade
Bangkok is the world's trading floor for ruby, but the heat happens two hours away in Chanthaburi, where side-street “burners” run the furnaces. Thailand's own Siam-ruby mines are spent — today's rough is mostly Burmese and, increasingly, African — and most of it needs treatment to sell at all. The honest flag every buyer should know: the lead-glass-filled “composite ruby,” perfected in Chanthaburi, fills a poor stone's cracks with so much glass that GIA refuses to call it a ruby — “a manufactured product consisting of glass and ruby” — and it can be etched by nothing stronger than lemon juice.
The ruby gemstone - SapphireCutTreatTrade
Sapphire follows the same road: Thailand's mines are largely worked out, so the rough now comes from Sri Lanka, Madagascar, Mozambique and beyond — and the country's real moat is the kiln. It is also where treatment once outran the laboratories: in 2001, vivid orange “padparadscha” sapphires flooded the market before anyone realised Tanzanian rough was being coloured by diffusing beryllium in at a few parts per million — undetectable, at first, even to GIA. It is exactly why the world's treatment-detection labs cluster in Bangkok.
The sapphire gemstone
Makers & Houses
Silom concentrates the full coloured-stone chain, mine-direct sourcing, in-house free-hand cutting, and consumer bespoke, into a handful of towers around the Jewelry Trade Center, where family houses that began as B2B rough dealers now cut, make, and sell to collectors under one roof.
The district's most famous names on Silom Road are trade institutions, grading labs and B2B bodies, not consumer houses. The provable maker-houses sit as tenants and by-appointment ateliers around them.
- Chanthaburi (treat)Treat
- Silom, BangkokCut
- Collectors, internationalSell
Veerasak Gems
วีระศักดิ์ เจมส์Known for certified loose coloured stones and jewellery, cut and disclosed in-house
A Silom-rooted, family-run house since 1980 that both cuts its own rough and sells to consumers and high-jewellery houses, with public RJC membership and disclosed origin and treatment.
Thai Native Gems
Known for custom-made rings and jewellery built to order, with GIA-graduate gemological advice
A Gupta-family house trading in Silom since 1960 and now a consumer-facing custom jeweller led by a GIA Graduate Gemologist, three generations of provable district presence with a live site.
Lambert Gems
Lambert Industries, Ltd.Known for custom-cut stones and made-to-order pieces sourced and built on request
A consumer-facing Silom atelier repeatedly cited by independent buyers for custom cutting and bespoke rings, a provable maker a visitor can actually commission.
BellaDonna Jewelry
Known for custom, handmade fine jewellery designed to order, with hotel pick-up or international shipping
A younger Silom-area bespoke house with a live retail site, showing the district still seeds new consumer-facing ateliers rather than only legacy dealers.
- AJS Gems · Silom coloured-stone dealer, ITF Tower; buys mine-direct, sells by appointment
- BangkokGemsMarket · Third-generation family gem dealer with a visitable showroom in the Jewelry Trade Center
- Jewelry Trade Center (JTC). A 59-storey wholesale and retail trade complex that anchors the district; a building operator, not a single shop.
- Thai Gem and Jewelry Traders Association (TGJTA). Trade association, est. 1978.
- Gem and Jewelry Institute of Thailand (GIT). National public grading lab, ISO/IEC 17025 accredited.
- Asian Institute of Gemological Sciences (AIGS). Gemology school and laboratory founded 1978.
- Lotus Gemology. Independent coloured-stone testing laboratory.
- American International GemLab (AIG). Gemological grading laboratory operating within the JTC.
- SSEF & Gübelin. Swiss laboratories offering services from the Silom 19 Building beside the JTC.
- Bangkok Gems & Jewelry Fair. Long-running international trade exhibition.
On the map
- Jewelry Trade Center (JTC), Silom Road
- Silom Road / Mahesak Road (the gem blocks)
- Bang Rak district
In the district
Walk the district
Traveller notes
Silom is a real trading hub, but Bangkok is also infamous for gem scams aimed at tourists — buy only from established dealers and insist on independent certification.
- The Jewelry Trade Center (JTC) on Silom — established dealers and labs under one roof.
- Thailand's specialty is treated rubies and sapphires — ask exactly what treatment a stone has had.
- Beware tuk-tuk "gem deals" and prices that seem too good — a classic Bangkok scam; get independent certification (e.g. GIT).
