Lab Technology

ED-XRF

Different technical and analytical methods are basics in a good gemological laboratory. Each method is useful for a specific application:

• Identification of natural gemstones and synthetics
• Different way a natural or synthetic stone is growing
• Identification of physical treatments (e.g. radiation)
• Identification of chemical treatments (e.g. Pb-fillings)
• Analyzing the chemical composition and trace elements
• Identification of the geographical origin of a gemstone

ED-XRF (Energy Dispersive X-Ray Fluorescence) was developed in the 1980's and has become one of the most important analytical methods. It is used in many applications today (e.g. metals & alloys, minerals, glass, color pigments, plastics, soil, food). The big advantage of this method is that no damage is caused to the sample. ED-XRF is the only absolute non-destructive chemical analysis. Each atom is analyzed in the gemstone or mineral on incident X-ray radiation. The resulting fluorescence signal produces a complete spectrum of all the elements in a gemstone. From Sodium (Na = atomic No 11) to Uranium (U = atomic No 92) all elements are precisely analyzed from 100% down to 0.0005%.

Three steps are important for excellent ED-XRF data:

The spectrometer is perfectly calibrated
The spectrum is the primary source of information
The analytical data is controlled by good standards

Applications:

• Separation of natural gemstones from synthetics.
• Analyzing enhancement methods in a gemstone.
• Analyzing the geographical origin of a gemstone.

FTIR

Fourier Transform Infrared Spectroscopy (FTIR) is used to obtain an infrared absorption or emission spectrum from a solid, liquid or gas.

Applications:

• Separation of natural gemstones from synthetics.
• Determining the presence of polymer-based impregnation, eg: Jade & Emeralds.

 

LIBS

Laser-Induced Breakdown Spectroscopy (LIBS) uses a highly energetic and focused Nd:YAG laser pulse to ionize a small number of particles on the sample’s surface. As this plume expands, the expelled particles become excited before almost immediately dropping back down in energy and releasing photons. As the specific frequency of this emitted light varies from element to element, LIBS can, in principle, determine the composition of any mineral.

Application:

• Detection of diffused beryllium within corundum (i.e. “new heat”) when present at quantities in excess of 2 ppm.

DFI

The DFI Mid-UV Laser a flexible, high-performance device for detecting HPHT and CVD synthetic diamonds of any size, and is able to test up to three thousand melee stones per hour.

Applications:

• Detection of synthetic colorless diamonds produced via both the CVD and HPHT methods.
• Detection of imitation diamonds.

UV-VIS-NIR

UV-VIS-NIR spectrometer is used to measure the light absorption and intensity in UV and white light. This measurement allows us to identify certain chemical elements in the sample.

Applications:

• Separation of natural Ruby, Sapphire and Emeralds from synthetics.
• Detecting the presence of trace elements to determine if the sample is Metamorphic or Basaltic.