Diamond Type Analysis
FT-IR analysis is a diamond's best friend
Since the rise of synthetic, nearly perfect imitation, and treated diamonds, it's become harder to determine a gemstone's true value. Infrared spectroscopy offers a simple way to classify diamonds and spot imitations. It helps identify whether a diamond is natural, synthetic, or treated using high pressure, high temperature (HPHT) methods.
- Universal technique: works for polished and rough diamonds
- Type Classification: Distinguishes natural, synthetic, or treated diamonds.
- Detect Impurities: Finds foreign atoms like nitrogen, hydrogen, or boron.
- Detect Synthetic/Treated Diamonds: Spots HPHT-treated or synthetic stones.
- Easy Classification: ALPHA II Analyzer enables fast, user-friendly testing.
- Batch Screening: HTS-XT accessory rapidly tests small stones.
- Microscopic Analysis: LUMOS II inspects small diamonds and jewelry.
How FT-IR spectroscopy analyzes diamonds
Knowing a diamond's type is crucial for identifying synthetic stones and candidates for HPHT treatment. FT-IR (Fourier-transform infrared) spectroscopy is a powerful method for diamond analysis that examines how infrared radiation interacts with diamond crystals to determine their type and quality.
This technique interrpets the unique vibrational signatures produced by foreign atoms such as nitrogen and boron, which create distinct absorption patterns in the infrared spectrum. The figure next to this text shows FT-IR spectra of different diamond types. Even an untrained eye can make out clear differences between the diamond spectra.
FT-IR helps to classify diamonds into two primary types based on nitrogen content: Type I, containing detectable nitrogen, and Type II, which does not. Subtypes, such as Ia and Ib, provide critical insights into a diamond's origin and treatment history. Understanding these types helps in detecting treatments and synthetic origins, ensuring accurate valuation. This can be done using the ALPHA II diamond analyzer or the LUMOS II microscope.
Step-by-step procedure
First, a background spectrum of the empty gold-coated sample holder is measured. Then, the diamond is placed in the center of the holder and inserted into the instrument. The software guides the user step-by-step through the process, making it simple and fast to complete.
FT-IR is a very fast, robust technique. The measurement and evaluation process takes less than 30 seconds. The result is shown along with the diamond's spectrum, providing a clear and quick analysis. Standard tools allow in-depth chemical analysis of the infrared spectra
After the analysis, the analyzer generates an automatic PDF report that can be opened with a single mouse click. This report includes all essential information, such as the spectrum, identification result (whether it’s a diamond), and type classification.
Rough and polished diamonds
The analysis of a diamond using Diffuse Reflectance Infrared Fourier Transform (DRIFT) begins by placing the diamond on a gold-coated sample plate within a specialized DRIFT unit. The results are compiled into a report detailing the diamond's classification and potential treatments, aiding gemologists and traders in assessing the diamond's value and authenticity.
Mounted Stones
Mounted stones from jewelry can be measured by using the ALPHA II with the forward looking reflection module. For the analysis, the stone just has to be placed in front of the aperture hole. A build in camera helps to position the stone correctly and thereby enables the user to selectively measure even smaller stones that are in a narrow arrangement. The inset shows a picture of a 0.25 carat diamond that was taken with the internal camera of the ALPHA II reflection module.
Very small mounted diamonds
The FT-IR microscope LUMOS II allows for the selective measurement of very small mounted stones in jewelry, even when they are in close contact. Its fully automated design and user-friendly operation provide efficient analysis with a large working distance of 30 mm, accommodating samples up to 40 mm tall without hardware changes. A specialized holder secures various types of jewelry during examination. The system enables accurate classification of diamonds and helps detect organic contaminants, making it an essential tool for gemologists assessing mounted stones.
