Gemstones in Thailand

Stone, source, and craft

Gem checks in Thailand do not rest on one paper. They form a chain of separate facts. One fact is what the stone is. Another is what a lab found when it tested that stone. A third is whether the report number is in the lab's files. A fourth is who sold the item. A fifth is what rules and written terms govern the sale. These facts can support each other, but none proves all the rest.

Thailand has a public gem lab for the first part of this chain. The Gem and Jewelry Institute of Thailand, or GIT, runs the GIT Gem Testing Laboratory. GIT says the lab is certified to ISO/IEC 17025. It is also recognized by CIBJO and belongs to the Laboratory Manual Harmonisation Committee. The lab can tell natural stones from man-made or imitation material. It can look for treatments. For some gems, it can also give an origin opinion. It tests diamonds, jade, pearls, loose colored stones, and jewellery.

A GIT report records what the lab found on the item sent for test. It can list the type of stone, size, weight, color, shape, cut, treatment, photo, and other notes. Some services can add an origin opinion. The report is so a record of a lab exam. It is not proof of every claim made by a seller.

GIT also has an online Report Verification service. This is a second step, not the same step. The service can show the report number and key fields from GIT's files. GIT says the online check covers items sent from 1 July 2014 onward. It also warns that some details for reports issued before 2024 may be incomplete after system changes. The key point is simple. A database check can show that GIT has a record for a report. It does not, on its own, prove that a loose stone shown with that paper is the same stone GIT tested.

Trade, treatment, and testing

Treatment is another separate fact. In 2010 GIT issued a guide on full disclosure in the gem trade. It said gem type, quality, and treatment need clear terms. It discussed heat and more specific work such as coating, dyeing, filling, oiling, resin, irradiation, and diffusion. The exact trade terms can change as science moves on. The basic rule does not: a treatment should not be hidden by vague naming.

This is why “natural” does not mean “untreated.” A natural ruby or sapphire may have been heated. A natural emerald may contain oil or resin in cracks. The stone can still be natural, but the treatment is a second fact about it. LMHC sheets help major labs use similar words for such findings. CIBJO's Blue Books also give the trade a shared set of names for natural, treated, man-made, and imitation material.

Identity and origin are separate too. GIA makes this clear in its colored-stone report system. One report type tells what the material is and lists treatment that can be found. Another can add an origin opinion when GIA offers that service and has enough evidence. An origin statement is so not built into every gem report.

This matters in Thailand because the country has deep skill in gem cutting and treatment. Bangkok and Chanthaburi are major centers for colored stones. Thai labs have had to track new methods as the trade changed. GIT's work on sapphire treated with heat and pressure is one example. It shows that labs may debate whether a new process can be told apart from an older one and whether it needs its own wording.

The seller belongs to a different part of the record. Thailand's Department of Business Development runs DBD DataWarehouse+. It lets the public search a Thai juristic person by name or registration number. DBD itself warns that this kind of record only confirms legal registration and related company data. It is not proof that each claim made by that business is true. A company can be real while a claim about a stone is still wrong.