Buying Gemstones in Bangkok: How the Trade Really Works

My office is in Bangkok because the stones are. Burmese ruby crosses the border here. African sapphire and ruby fly in from Nairobi, Antananarivo and Maputo. Sri Lankan parcels arrive with the traders who own them. Nearly all of it is cut, a great deal of it is heated, most of it is papered, and then it leaves again for Geneva, Hong Kong, New York and Mumbai with a Bangkok invoice attached. If you buy a fine coloured stone anywhere in the world, the odds are good it passed through a building within a kilometre of my desk.

Where the trade lives

The coloured stone trade sits in the office towers off Silom and Surawong, in rooms with north-facing windows and a safe, and in the streets around them where runners carry parcels between dealers in their shirt pockets. There are no signs worth reading. The men and women who matter have been in the same rooms for thirty years and do not need to advertise. A few kilometres east, the weekend market in Chanthaburi is where the heating and much of the cutting happens; parcels go there rough and come back cut, cooked and ready.

The gem fairs bring the world in twice a year, and they are worth walking for what they teach about price. But the serious stones do not sit in a booth. They are shown in an office, to one buyer at a time, with the door closed.

The three traps

The first trap is heat. Most sapphire and ruby in this city has been to a furnace, and the furnace leaves no sign a visitor can read. A heated stone sold as heated is honest work. A heated stone sold as unheated is the most common fraud in the trade, and it is committed with a smile and a certificate from a laboratory you have never heard of. The only defence is a report from a house whose name you know, and the discipline of sending the stone there yourself before you pay. I have set out what the unheated premium buys and why it is worth paying for; the point here is that the word is worthless from a seller’s mouth.

The second trap is glass. Low-grade corundum from Africa, fractured and opaque, is filled with lead glass and sold as ruby at a fraction of a ruby’s price. Under a loupe it shows bubbles and a blue flash at the glass; under a jeweller’s torch it falls apart. The traps deserve their own note. Here it is enough to say that if the price of a red stone seems impossible, it is.

The third trap is the story. Bangkok runs on stories: the old Burmese family parcel, the Kashmir stone from an estate, the miner who needs to sell today. Some of them are even true. None of them changes the stone. I judge the stone in my own light against my own masters and let the story be a story.

The light and the paper

Two things change the odds in this city. The first is light. I never judge colour in a seller’s office lamp, and I have written about why the lamp is warm. A daylight torch, master stones and a walk outside settle in four seconds what a warm bulb can argue about for an hour. The second is paper, in the right order: what the stone is, what has been done to it, where it likely formed, and only then whatever colour name the house chose to grant. Reading the report properly is a skill, and most buyers read it backwards.

For the top of the market, Bangkok paper is not enough. GIA and GRS have laboratories here, and Lotus Gemology and AIGS are Bangkok houses, all of them serious. But the auction rooms speak Swiss, and a stone that will one day be sold in Geneva should carry a Gübelin or SSEF report from the start.

What a fair price looks like

There is no list price for a fine coloured stone, but there is a logic. Price per carat climbs with weight, steps at the round numbers, and multiplies again for origin and for the treatment line. A dealer here will quote in dollars per carat and expect to be argued with; the first number is an opening, not a price. A visitor without a reference will pay the opening. A buyer with master stones, a laboratory account and the patience to leave the room will pay something closer to what the stone is. The difference is usually the price of the flight, several times over.

Why an independent buyer matters

The dealers of Silom are not villains. They are traders, and a trader’s job is to sell what he holds at the best price he can get. Your interest and his coincide only by accident. An independent buyer who holds no stock, carries his own light, sends every stone to the laboratory before money moves and has spent years learning which rooms to walk into is not a luxury in this city. He is the difference between buying a stone and buying a story about one.

Bangkok will sell you anything. The trick is to arrive already knowing what you want, in a light you brought yourself.

Questions collectors ask

Is it safe to buy gemstones in Bangkok?

It is safe to buy from serious dealers with a laboratory report from a house you recognise, in daylight, at a price that makes sense for what the report says. It is not safe to buy from a tour-bus showroom, from a stranger with a story, or from anyone who will not let the stone go to an independent laboratory before you pay. The city is the same for everyone; the outcome depends on the light and the paper.

Should I buy at the Bangkok gem fair?

The fairs are useful for seeing what is trading and at what price. They are less useful for buying, because a fair price is a trade price for the trade, and a visitor rarely gets it. Serious purchases happen in offices, over days, with the stone leaving for the laboratory before money moves.

Which gemmological laboratories operate in Bangkok?

GIA and GRS both have Bangkok laboratories, and Lotus Gemology and AIGS are based here. For the top of the market, stones still travel to Gübelin or SSEF in Switzerland, because that is the language auction houses and their buyers speak.