SERVICE
SERVICE

Precious Metals

Service Introduction

Precious Metal Inspection Laboratory has opened a quality inspection and engraving service. (Hallmarking) gold, platinum, silver and other precious metals. Since May 2003, using the most advanced equipment including Inductively Couple Plasma Optical Emission Spectroscopy (ICP-OES) and X-Ray Fluorescence (XRF) to verify purity and laser marking to engrave quality certificates. gold and other precious metals The budget is supported by the government's economic stimulus fund. The establishment of the center This precious metal inspection is aimed at protecting consumers. build consumer confidence prevent fraud and encourage honest competition It also supports the mission of the Faculty Office. Committee on Consumer Protection (OCPB) to inspect the purity of jewelry products and assist tourists according to the wishes of the Tourism Authority of Thailand (TAT).

Contact

Gem Testing Laboratory, The Gem and Jewelry Institute of Thailand. (Public Organization)ITF Tower, 4th Floor, Silom Road
Suriyawong, Bangrak, Bangkok 10500

Telephone 0 2634 4999 ext. 421-423
Fax 0 2634 4970
Email jewelry@git.or.th

Business hours
Monday - Friday, 8:30 a.m. - 4:30 p.m. except Saturday - Sunday, public holidays. and holidays as announced by the institute

1. Workpiece destruction type Divided according to methods and tools used in the analysis as follows:

  • Fire Assay technique
              The technique of separation gold from impurities by melting the impure metal in a cupel (a flat, porous dish made of a refractory, or high-temperature-resistant, material) and then directing a blast of hot air on it in a special furnace. The impurities, including lead, copper, tin, and other unwanted metals, are oxidized and partly vaporized and partly absorbed into the pores of the cupel. Separation of silver by acid.  To weight between before and after analyzing and comparing. This is the traditional method used in assaying the content of gold samples.

    This technique is suitable for Gold Jewelry, Gold Dip, Gold Rod, Gold sheet.
     
  • Potentiometric Titration (Auto Titration)
              Potentiometric Titration involves measuring the changes in the electromotive force brought about by the addition of titrant of precisely known concentration to the test solution (silver dissolved in Conc. Nitric Acid). Silver/Alloy is weighed accurately to one-hundred thousandth of a gram. The silver sample is placed in the beaker. The sample is dissolved in 5 ml conc. Nitric Acid, warmed, and allowed to cool. Samples are then analyzed by Potentiometric Titrator as follows ; Titrant is added automatically via a burette. A silver electrode detects the change in electrical conductivity of the solution until it finds the end of point of the titration, when all the silver has been precipitated. The amount of Titrant needed to reach this end point shows how much silver was present in the original sample.

    This technique is suitable for Silver Jewelry, Silver Dip, Silver Rod, Silver sheet.
     
  • ICP-OES (Inductively Coupled Plasma Optical Emission Spectrometry)
              The precious metal content can be accurately determined using ICP-OES (inductively coupled plasma with optical emission spectrometer). To this end, the homogeneous solid is converted to a liquid sample. The elements contained within it are then separated and a plasma flame can be used to make them visible. The relevant precious metal contents can then be determined.

    This technique is suitable for
         - Heavy metal ; Ni (Nickel), Cd (Cadmium), Pb (Lead)
         - Fine Jewelry ; Fine Gold, Fine Silver
         - The Composition of Jewelry
     

  • Nickel Release

              Nickel Release Method is the internationally recognized nickel testing and analysis method used to determine the rate of nickel release from jewelry, metals and other items. The nickel test was devised to assess whether articles comply with the requirements of the EU Nickel Directive. In any post assemblies that are inserted into pierced ears and other pierced parts of the human body. The rate of nickel release from such post assemblies is less than 0.35 µg/cm2/week (migration limit).

              In products intended to come into direct and prolonged contact with the skin, such as earrings, necklaces and wrist-watch cases. The rate of nickel release from the parts of these products coming into direct and prolonged contact with the skin is less than 0.88 µg/cm²/week (migration limit).
     

2. Non-destructive type Divided according to methods and tools used in the analysis as follows:

  • X-Ray Fluorescence technique
              X-ray Fluorescence (XRF) is a non-destructive analytical technique that uses the interaction of X-rays with a material to determine its elemental composition and concentration. When X-rays irradiate to the surface of the sample, some of the X-rays pass through it, and some are absorbed in the sample.      The excited electrons from a higher energy fall into the lower energy position, the excess energy is emitted in the form of fluorescent X-rays. The energy difference between the expelled and replacement electrons is characteristic of the element atom, so this technique can be used to analyze both composition and concentration from spectral peak and their intensity respectively.

    This technique is suitable for Analyze the metal content of a sample which is non-destructive technique in a short period of time.
     
  • X-Ray Fluorescence (XRF)
              This service provides the thickness of plating or coating measurement by using X-Ray Fluorescence (XRF). The clients have to give us a sample before and after coating including the method of coating for setting the application used to measure the thickness. However, if there is no the sample before coating, we provide laser on the sample’s surface service to mark the point to be the area without coating.

    This technique is suitable for

         - Measure the thickness of coating layer and report “μm (micrometer, micron)”as a measurement unit.

         - The information about coating method is very essential to get the accurate analysis. 
     
  • X-Ray Fluorescence (XRF)
              This service provides a composition and concentration on plating or coating measurement by using X-Ray Fluorescence (XRF). The clients must give us a sample before and after coating including the method of coating for setting the application used to measure the sample. However, if there is no the sample before coating we provide laser on the sample’s surface service to mark the point to be the area without coating.

    This technique is suitable for

         - Measure the composition and concentration on plating or coating layer and report “%”as a measurement unit.

         - The information about coating method is very essential to get the accurate analysis.
     
  • Ultrasonic Testing
              Ultrasonic Testing (UT) uses high frequency sound energy to conduct examinations and make measurements. The sound energy is introduced and propagates in the form of waves. When there is a discontinuity (such as a hole or crack) or different compositions in the wave path, part of the energy will be reflected back. The reflected wave signal is transformed into an electrical signal by the transducer and is displayed on a screen. These waves will give the homogeneity information.

    This technique is suitable for
         - Measure the homogeneity of a sample which has a large size and flat surface such as gold bars, statue of Buddha. In general, this technique combined analyzes with X-Ray Fluorescence (XRF).
     
  • Hallmark
              Hallmarks are small stamps made on the surface of the sample that contain precious metals. They identify and categories the purity of the precious metal used in any given piece.

Reporting

Analysis and inspection report divided into

1. Thai audit report

Indicates the type, type, weight and description of the sample. Analytical techniques and purity values
of precious metals in Thai language

Sample of report in Thai

2. Examination Report in English

Sample English result report

3. Image inspection report

Sample report with pictures

4. Jewelry Report inspection report

Example of a result report with pictures