Thailand is recognized as one of the world's major gem and jewelry centers. The Kingdom is not only blessed with dedicated and talented craftsmen but also with large gemstone deposits.
Sapphires were discovered in Kanchanaburi, Chanthaburi, Si Saket, Ubon Ratchathani, Phrae, Phetchabun and Sukhothai. The Nam Yuen district in Ubon Ratchathani and Chanthaburi Pong Nam Ron's districts, Bo Rai and Khao Saming are known as producers of rubies as well. The red rubies from Chanthaburi known as "Tab Tim Siam" or "Siamese Rubies" are in demand for their bright red and her magical appearance with lovers from all over the world. Thai rubies have therefore earned Thailand the reputation as the "Land of the gems of the East".
Thailand's gem and jewelry industry has been systematically developed from a small business section to a large export-oriented industry. The gem sector has become a major foreign exchange earner generating billions of Baht year by year, creating jobs for hundreds of thousands of people.
Over the years, Thailand has developed into one of the five leading gem cutting centers. The other four are Israel, Belgium, the United States and India. The cutting skills of Thai craftsmen improved to a great extent over the time developing the world-renowned “Bangkok cut”.
Quality, attention to detail and reasonable pricing are the elements of a sustained success of the Thai jewelry industry. To improve the competitiveness of the sector the Royal Thai Government has lifted tariffs on imported raw materials.
In addition, the government made the purchase of Thai gems and jewelry even more attractive to foreign buyers by refunding value added taxes (VAT). The currently applicable conditions for a VAT refund are as follows:
- Purchase in shops with the label "VAT Refund for Tourists"
- Personal export of the goods within 60 days from the date of purchase
- The daily minimum purchase value is 2,000 Baht - The total value of purchased goods for getting a VAT refund is at least 5,000 Baht
- The seller provides a form for VAT refund with two copies of a tax invoice
- VAT refund cannot be claimed on weapons, explosives etc., and unset gemstones
- The goods must be presented to the customs officials upon departure
The quality of Thai jewelry is guaranteed. The retail sale of gems and jewelry is regulated by strict trading conditions enacted by the government and industry organizations. The quality of gems and jewelry is assayed and warranted by internationally recognized local bodies such as the Asian Institute of Gemological Sciences (AIGS), the International Gemological Institute (IGI), the Gem and Jewelry Institute of Thailand and other institutes. The strict testing procedures and the issue of certificates guarantees the quality of the items purchased.
List of Institutes
- Department of Mineral Resources Physics Section, Rama IV Rd., Phayathai, Bangkok 10400
Tel: 202-3690
Fax: 202-3681
- The Gems and Jewelry Institute of Thailand Faculty of Science Chulalongkorn University, Phayathai Rd.
Bangkok 10330
Tel: 218-5030-2
Fax: 253-0337
- Asian Institute of Gemological Science (AIGS) Jewelry Trade Center Bldg. 6m Floor. 919/1 Silom Rd. Bangkok 10500 Tel: 2674325-7
Fax: 267-4327
- International Gemological Institute (IGI) B.G.I. Bldg. 9, Soi Charoenkrung 36,New Road, Bangkok 10500
Tel: 630-6726-7
Fax: 630-5030-2
- Tokyo Gem Laboratory (Thailand) Co., Ltd. 1 Floor, 55/11 Soi Charoenkrung 42/1, New Road, Bangkok 10500
Tel: 235-1667-8, 235-7324
Fax: 630-9735
Selection and nature of gemstones
To begin with, it is important to gain a basic knowledge about the characteristics, colours, clarity, style, cut and weight of the gemstones you are going to select. Generally speaking, there are two categories of gemstones - precious and semi-precious stones.
The diamond, ruby, sapphire, yellow sapphire, emerald and cat's eye belong to the precious stones category. Semi-precious stones include, among others, tourmaline, peridot, tanzanite, garnet, opal, spinel, zircon, aquamarine, moonstone, agate, pearl and sunstone.
The commercial value, hardness and durability of semi-precious stones is generally less in semi-precious stones than in precious stones.
Ruby
Its color ranges from dark red to pink. The hardness measured in Mohs is 9; the refraction index is 1.762 to 1.770 (+ / - 0.009 - 0.005) and the specific gravity is 4.00 (+ / - .10 to .05) This gemstone has its origins in countries such as Thailand, Cambodia, Myanmar (Burma) Vietnam and Tanzania.
Blue Sapphire
This gemstone has properties similar to the ruby in terms of color, hardness and density. The blue sapphire has its origin in Thailand, Cambodia and Myanmar (Burma).
Yellow sapphire
The yellow sapphire has specifications like the blue sapphire and the ruby and is mostly found in Thailand and Sri Lanka.
Diamond
The diamond is found in Africa, Australia, Russia and South America. It is generally colorless, although some diamonds are found in bright yellow and brown colors. Its hardness is 10 Mohs; the refraction index is 2.417 and its specific gravity 3.52 (+ / - 0.01).
Quality and value of gemstones
The value of a gemstone is measured by its beauty, colour, luster, transparency, clarity, perfection of cutting, size, durability, and rarity.
Ruby
The most valuable ruby is pigeon’s blood red. Stones with dark to purple red colours are of lower value. Rubies with good transparency are considered beautiful and have more value than others. The value of a ruby can also be assessed by its clarity, which is usually an essential feature of the stone, and its shape. Another beauty feature are star-like "asterisms" in a stone, hence the name "Star Ruby". The star is best visible when a ruby with a cabochon shape (a convex dome top with a flat bottom) is exposed to a light source.
Blue and Yellow Sapphire
The most expensive blue sapphire exhibits a "pure" blue without any green or gray tints, and which is not too dark or too black. The most beautiful colour of a yellow sapphire is a dark yellow and a golden brown. The popularity of these two colors vary from market to market, depending on tastes and fashion trends. Blue and yellow sapphires with good transparency and clarity are of more value; however, size is a determining factor, since it is easier to find a larger blue or yellow sapphire than a ruby. As the ruby, the blue sapphire exhibits a “star”, while it is rare to find in a yellow sapphire.
Diamond
The most common colours of diamond range from light yellow to light brown, while white diamonds are rare. The larger a diamond is the higher is its value; and a well-proportioned diamond that reflects light looks more brilliant and is therefore more expensive.
Indication of weight for gold, precious stones and diamonds
The weight of gemstones and diamonds is measured in carats and grams. A carat is equal to 200 milligrams, while a gram is 5 carats or 1,000 milligrams. Karat in gold measurement is usually written with a capital “K” or “Kt” to provide a distinction from "carat" for precious stones measurement.
Certificates for precious stones and jewels
A certificate of authenticity for purchased jewelry is usually issued by a laboratory. However, such certificates might also be issued by specialists who underwent training at a Gemological Institute and who are employees of a jeweler. With the growing use of synthetic stones in jewelry it is crucial that buyers do insist on a certificate of authenticity being issued by an authorized gemologist of a store in which the purchase is made.
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