Material

Diamond Type Ia	~2×10³ ppm of nitrogen – yellow
Diamond Type Ia – Raman low / ultra low fluorescence	~2×10³ ppm of nitrogen – white to light yellow
Diamond Type IIac	~1 ppm of nitrogen – white to light brown
Diamond Type IIas – Raman ultra-low fluorescence & ultra-low birefringence	~1 ppm of nitrogen – white

Almax easyLab is committed to its policy of continuous improvement.  Specifications may change without notice. easyLab and Diacell are registered trademarks of Almax easyLab.

FT-IR Spectrum

FLUORESCENCE

Almax easyLab can select its diamonds for low fluorescence. Standard measurements include laser excitation at 532 nm and covers fluorescence background in the range of 542 to 608 nm (Raman shifts between 1000 and 3000 cm-1). Measurements for different wavelength ranges can be made available on request. In special cases customers can select their own diamonds for low fluorescence using their own measurement set-up.

Almax easyLab classifies its diamonds with respect to fluorescence according to the following criteria:

• Type Ia UV low fluorescence – Checked with a UV lamp

• Type Ia Raman low fluorescence – The intensity of the two-phonon Raman transition at 2664 cm-1 is at least 1.25 times the intensity of the background fluorescence of diamond

• Type Ia Raman ultra-low fluorescence – The intensity of the two-phonon Raman transition at 2664 cm-1 is at least 2 times the intensity of the background fluorescence of diamond

• Type IIac Raman ultra-low fluorescence 

BIREFRINGENCE

All diamonds to be used for anvil manufacture are examined under a polarising microscope for birefringence. Diamonds with significant birefringence discontinuity, typical of inclusions, etc. are rejected. In addition diamonds can be selected for ultralow birefringence. Total birefringence is measured using crossed polarisers, a waveplate and matched to specifications. Normally:

• Low birefringence <0.0001
• Ultra low birefringence <0.00005