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GIA UV Lamp and Viewing Cabinet
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GIA UV Lamp and Viewing Cabinet
Room Light Requirements
Use the GIA UV Lamp and Viewing Cabinet with standard and stable room lights or
at lower light levels, if possible, to improve visual observation of fluorescence. While
the cabinet provides a relatively dark environment by design, excessive lighting may
diminish the contrast effect of the cabinet chamber. Using the device in direct sun-
light or in very bright areas will make it difficult to adequately observe fluorescence
in the viewing cabinet. Also avoid placing stone papers or other paper materials in
the cabinet along with gemstones as they tend to fluoresce very strongly and may
interfere with the user’s observations of diamond fluorescence.
The Light Source
One of the biggest advantages of the GIA UV Lamp and Viewing Cabinet is the
incorporation of a narrowband 365 nm UV LED as a light source. Most UV lights
available in the trade are based on mercury lamps with consumable filters that
control the energy of UV light emitted. The filters allow additional UV and visible
light to be emitted (along with the standard longwave UV at 365 nm) and degrade
relatively quickly to allow even more light contamination. In addition, 365 nm
UV light emissions tend to be very broad, often encompassing an energy range
as wide as 340-390 nm. Light contamination and different wavelengths of UV
emission causes variation in both the color and intensity of fluorescence produced
in diamonds. The 365 nm UV LED incorporated into the GIA UV Lamp and Viewing
Cabinet has a single emission at 365 nm with a FWHM (Full Width at Half Maximum)
value of 9 nm. This narrowband emission provides an accurate and reproducible UV
light source for consistent viewing of diamond fluorescence. The UV LED is also very
long-lived with an estimated lifetime of 60,000 hours.
The Reference Block
The GIA UV Lamp and Viewing Cabinet comes with a specially calibrated reference
block (patent pending) to assist the user in estimating fluorescence grades
for diamonds with blue fluorescence. The block consists of four openings that
represent, in order from left to right, the upper limits for GIA’s “None/Very Faint,”
“Weak,” “Medium,” and “Strong” grades for blue fluorescence in diamond. These
visual references are calibrated based on the results provided by GIA laboratories
worldwide on diamond reports.
The fluorescent strip of paper inside the reference block will decrease in intensity
with usage and must be replaced on a regular basis. After 40 hours of cumulative
exposure to the LED UV light, the paper should be replaced. Depending on the use
of the lamp and reference block, a single paper strip may last from one week to
one month, but should be changed at least monthly. Thirty-six replacement paper
strips are included with each unit in an opaque envelope. Additional replacement
paper strips should only be purchased from GIA. If any other paper is used, the
calibration of the reference block will NOT be consistent with GIA standards and
the fluorescence grade estimations will be off.
To replace the paper strip, simply unscrew the two small screws on the top of the
reference block with the hex key provided, remove the old strip and replace it with
a new one with the matte finish surface facing upward. Reassemble the block by
tightening the two screws and the paper change is complete. In order to maximize
the life of the reference block paper by limiting its exposure to the LED UV lamp,
we recommend removing it from the viewing cabinet when not being used as
a reference.
