Diamond Gemology

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• Day-light Lamps
• Color-Grading Equipment - Colorscope
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  • Color -Grader
  • Diamond Lite
• color-Measuring Instruments - Electronic Colorimeter
  • Remission Spectrophotometer
  • Diamond Photometer

Day-light Lamps

the foregoing section it has been indicated that the right light source is one
of the most important essentials for color-grading.

Various good artificial light sources are now available, among which DIALITE (an Eickhorst System) can be recommended in most cases. It is a practical and optically proven work lamp. With a color temperature of 5500° Kelvin (D55), its three 8-watt daylight- special tubes meet the RAUCIBJO standard. They produce a bright but dazzle-free daylight. Three light intensities can be switched on to accommodate eyes of varying sensitivity. The newly designed jointed arm allows easy upward or downward adjustment for the required working position. The DIALITE lamp is installed on a heavy base, with various table attachments and a wall holder (Fig 6)

Fig 6 Day-light lamp DIALITE

The light source produces a diffuse light, equivalent to North daylight (or South, in the southern hemisphere), its spectral distribution and intensity remain practically constant and are reproducible every time. As a result, the colored reflections and spectrum colors caused by the high dispersion of diamond which, according to the preponderance of yellow or bluish reflections in the daylight s8ectrum, can effect the resultant color positively or negatively, are largely Suppressed. The actual body color emerges more clearly. The lamp scarcely heats up at all and so permits a longish working time near the object under observation. The lamp does not produce any tiresome humming noise, so that it can also be used as an ordinary table- and work-lamp; it is also very suitable as a light source for clarity-grading.

	In addition to the two light tubes the lamp is fitted with a long-wave ultra-violet tube, which emits light through a black filter glass above the lamp housing, so that the fluorescence can be examined comfortably with the color in the course of a working session (Fig7).
Fig 7 Examination of fluorescence with analysis lamp

There is also the "Antwerp" work lamp, which possesses a higher red component in the spectrum and, as a result, emits a somewhat yellow light, which makes the color stages with lower yellow saturation In particular appear in greater contrast.

Summary of instructions on practical color grading

Colorscope