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Thailand Gems: Chanthaburi, Kanchanaburi, Phrae, & Trat

The Gemstones of Thailand

Article Copyright © 2012 AllAboutGemstones.com

Thailand (formerly the Kingdom of Siam) is a major worldwide gem trading, gem processing and gem treating center, with the cities of Chanthaburi and Bangkok at its hub. Thailand's gem and jewelry exports are expected to reach $4.75 billion US in 2008 [6]. Known primarily for its ruby and sapphire, there are several other notable gemstones that are mined in Thailand, such as amethyst, aquamarine, garnet, spinel, and zircon.

Map of Thailand

   Chiang Rai Thailand

Chiang Rai (photo: public domain)

Gem mining in Thailand occurs in three primary regions: Chanthaburi and Trat Province in the south-east pert of the country, Kanchanaburi Province in the west, and Phrae Province in the north. Chanthaburi and Trat boarder on Cambodia's Pailin region, which is also known for its high-quality ruby and sapphire.

Sapphire & Ruby from Chanthaburi

The small city of Chanthaburi (population 50,000), like Ratnapura in Sri Lanka, is one of the famous "gems towns" of South-East Asia. The famous weekend market in Chanthaburi (aka Muang Chan, or the "City of Gems," "City of Gem") sells gems from as far away as Madagascar, Mozambique and Tanzania, with many having been heat-treated in Chanthaburi's gem treating/polishing factories. Gem polishing is primarily a cottage industry in Chanthaburi, with factories spread throughout the city, but there are also many companies with a global reach, like Thaigem Global Marketing Ltd. which is located in Chanthaburi's "Gem Center" complex.

Kanchanaburi Province

Kanchanaburi Province (photo: public domain)

   Loose Gems of Thailand

Loose gems from Thailand (photo: public domain)

Outside of the city, sapphire and ruby mining in the Chanthaburi Province (aka Changwat) is located near Aranya Prathet (aka Aranyaprathet), along the Chanthaburi/Aranyaprathet-Poipet boarder with Cambodia, some 280 km east of Bangkok. The Chanthaburi region in known primarily for mining rubies (known as Siam Ruby), and secondarily for yellow sapphire, or black star-sapphire. Mining is conducted along ancient river-bank clay and gravel alluvial deposits, using both mechanized mining, and small-scale mining with hand-dug pits.

Rubies are found at a depth of 3 to 6 feet, and hand-digging is easier during the monsoon season when the ground is softer. Mechanized operations use water jets and sluicing to remove mud and clays from the gravel so that the hand-sorting process can take place. As in Sri Lanka, conical-shaped baskets are used for sluicing, which separates the heavier gems from the lighter gravels and sand.


Trat (photo: public domain)

   Gems Center

Mahesak Gems Center (photo: public domain)

Larger mechanized mines in Chanthaburi are the Bon Rai ruby mine and Nong Bon ruby mine, approximately 10 km from the Cambodian boarder. Small-scale pit mining is conducted in the Ban Bo I-Ram, Bo Na Wong, Bo Waen, and Wat Tok Phrom mining areas. Chanthaburi is also host the yearly Chanthaburi World Gem Show [5] which is held in mid December.

Sapphire & Ruby from Trat Province

The eastern Thai province of Trat is situated just to the south of Chanthaburi Province, bordering with Cambodia to the east, and Malaysia to the south. Until the crash of the ruby market in Myanmar in the 1960s, there was little interest in the darker, lower-quality rubies from Amphoe Bo Rai, in Trat. The Trat Bo Rai ruby mines are mostly hand-dug open-pit mines in alluvial clays and gravels, but there are also some mechanized operations in the region. When Cambodia began flooding Trat with rubies, Bo Rai became an overnight ruby boom-town.

Sapphire & Ruby from Kanchanaburi

Known for its famous "bridge over the River Kwai," and its deep-blue sapphire, Kanchanaburi Province is located on the western edge of Thailand, 128 km west of Bangkok. Sapphire and onyx mining in this region occurs at the alluvial pit-mines of the Kanchanaburi Bo Phloi (Amphoe Bo Thoi, Amphoe Bo Phloi, bo Ploi tambon) district, 30 miles north of Kanchanaburi Town. Sapphire in Kanchanaburi's Bo Phloi region was discovered in the early 1900s, and is one of the main sources to this day. Kanchanaburi is known for its deep-blue sapphire, which can have a dark, or "inky" appearance.

Floating Market in Thailand

Chao Phraya Floating Market

   Chanthaburi River in Thailand

Chanthaburi River (photo: public domain)

Sapphire & Ruby from Phrae Province

The Phrae sapphire mines in Phrae (Wiang Kosai) are situated along the Yom River, about 550 kilometres north of Bangkok. Phrae is one of the oldest cities in northern Thailand, which was part of Lanna Thai Empire that spans 800 years. The ancient cities of Sukhothai and Chiang Mai are located within Phrae Province, built by the Tai Lue people. The Burmese influence in this region is reflected in the architectural style of the Wat Chom Sawan and Wat Luang Buddhist temples.

Mae Sot

The city of Mae Sot in the north-western part of Thailand is another gem-trading center that boarders Myanmar's Karen State, giving it easy access to the Burmese Mogok ruby and sapphire trade, as well as Mawsitsit jadeite from Hpakant, Burma.


No discussion of the gem industry in Thailand would be complete without mentioning Bangkok, which is a powerhouse in the Asian gem-trading business. Over 70 global gem-trading firms are centered around the new "Gemopolis Industrial Estate" (aka: Gemopolis Mall, GIE, or "Gemopolis City") near Bang Na. Gemopolis was founded by Boonyong Assarasakorn in 1990, and in 2007 it accounted for 20 percent of all Thai exports, amounting to over $500 million worth of foreign exchange earnings [6].

The other gem center in Bangkok is the Silom-Mahesak-New Road area and its Oriental Plaza and River City shopping complex. Bangkok also hosts the internationally known "Bangkok Gem and Jewelry Fair" [7] in February and September.

Sapphire & Ruby from Pailin, Cambodia

For three decades after the Viet Nam war, the Khmer Rouge kept total control over the Pailin ruby mines, in order to finance its regime. Aggressive mining has severely depleted the supply of Cambodian ruby in recent years.

Heated Gem Material from Thailand

Thai gem-cutters have become experts in the heat-treatment of rubies and sapphire, over the last few decades. As much as 90% to 100% of the sapphire originating from Thailand may have been heat treated, diffusion treated, or both.

Thailand's Muang Chan's (Chanthaburi's) 'weekend market,' and the Trat province rough gem markets sell sapphire heated in Thailand, but originating from Laos, Madagascar, Sri Lanka, Tanzania, and Vietnam.

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Bibliography on the Gems of Thailand

1. Richard W. Wise, Connoisseur's Guide to Precious Gemstones . Brunswick House

2. John C. Wu, The Mineral Industry of Thailand . minerals.usgs.gov

3. John C. Wu, The Mineral Industry of Thailand . minerals.usgs.gov

4. TGJTA Thai Gem & Jewelry Traders Association . www.thaigemjewelry.or.th

5. Chanthaburi Chanthaburi World Gem Show . www.cga.or.th

6. Thailand Investment News Gemopolis Industrial Estate . www.boi.go.th

7. TGJTA Bangkok Gems & Jewelry Fair . www.bangkokgemsfair.com

8. Gemopolis Gemopolis kicks off Free Zone . www.gemopolis.com

9. V. Pardieu, J.B. Senoble, Ruby Sapphire mining in South East Asia . www.fieldgemology.com

10. Richard W. Hughes, Ruby and Sapphire . RWH Publishing

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