A few years ago, the Accredited Gemologists Association (AGA)
organized a lighting task force that investigated the impact of lighting on the
grading of fluorescent diamonds. Debate ensued, there was some positive impact,
but then the discussion abated and little was done. The time has come to
revisit this important topic.
Whether or not a diamond fluoresces, whether or not it is a good
thing or a bad thing, and how it affects what consumers are getting and paying,
are all issues the trade needs to address. Fluorescence is probably the
least-understand of all the factors affecting a diamond’s appearance and value,
and confusion and misunderstanding are rampant.
No one can begin to understand or address the issues however
without understanding the root of the problem: the lighting used to determine
the color grade, and how changes over the past few decades have actually caused
most of the problems we have today.
So here is a
brief summary of some of the findings from a research project undertaken
by the AGA (see www.accreditedgemologists.org
for
for the full
story and research findings/conclusions).
FACTS:
·
The color
shown on many diamond grading reports issued by labs globally indicates the
color seen only when exposed to sufficient UV emission to excite a
fluorescent reaction.
·
This
is NOT the color usually seen when worn by consumers; a fluorescent
reaction is usually only excited when the diamond is worn outdoors, during
daylight hours. Given today's lifestyles, most
people spend most of their time indoors during the day.
· This is NOT the color that will be seen when worn at night,
whether indoors or outdoors.
CONCLUSION:
·
UV emissions
should be eliminated from the lighting in
which diamonds are being graded because failure to do so results in
over-grading of diamonds with "medium," "strong," and
"very strong" blue-fluorescence--which
account for close to 10% of all diamonds sold
·
UV emissions
should be eliminated from the lighting in
which diamonds are being graded because failure to do so results in under-grading of the inherent body
color – the color most often seen when worn today – in yellow fluorescent
diamonds.
Blue
and yellow are the two fluorescent colors most often
present. Today, diamonds that fluoresce yellow will show their
inherent – and whiter – body color in most environments in which diamonds are
worn today; and in outdoor daylight, when fluorescence is stimulated, yellow
diamonds often look more fiery and possess a “warmer” color, that may be
desired by many diamond buyers.
·
Over-grading
results in over-pricing, even with discounts. The time is not far away when this will be the center of another
media exposé charging consumer fraud.
·
Grading in a
UV-free lighting environment will provide the color that best reflects the
color most often observed, and as was
done historically, is in the best interest of consumers.
·
Diamond grading reports that
indicate the "stable" color of the diamond as its grade (that is,
when no fluorescence is excited,) with a comment that the diamond may look
whiter in some lighting environments will remove the negative association
now connected with fluorescent diamonds.
A
strong negative association to fluorescent diamonds is pervasive because
of information on the internet and elsewhere. Retailers already see consumer avoidance
because consumers believe there is "something wrong" with
them, and that prices are inflated
for what they are getting. Currently prices are too high because the price is based
on an inflated color-grade. Grading the inherent body color (the color seen
when the diamond’s fluorescence is not
excited) will eliminate over-grading and over-pricing, and with this we will
also see a reversal of the negative bias.
In
summary, fluorescence in any fluorescent diamond is not being
excited when it is worn in most indoor environments--which is where
most people see their diamonds, most of the time, given today's life
styles.
Regardless
of indoor lighting conditions, there is insufficient UV emission to stimulate
the fluorescent response of a diamond. Just think about it: if indoor lighting produced enough UV emissions to
excite a fluorescent reaction, and we exposed to them all day, every day, we'd
all be dying from cancer!
The color indicated on a grading report for
a fluorescent diamond graded under UV emissions is not always
representative of the color seen outdoors. Sometimes the color is even whiter than indicated, even when
the grade on the report is "D"; a couple diamonds in the AGA study
that had been graded D and E actually appeared “light blue" oudoors in
daylight! [This
results from a number of variables affecting the intensity of the UV radiation to which the diamond is being exposed
– which is affected by such variables as time of day, altitude, air pollution,
and so on – and the strength of the diamond’s fluorescent reaction. Thus, the
fluorescent reaction can be stronger or weaker than the conditions present in
the diamond-grading light unit under which the color was graded.]
Industry
organizations continue to argue about this, but the science is
irrefutable. There are insufficient wavelengths of UV to stimulate a
fluorescent reaction in fluorescent diamonds when worn indoors; regardless
of whether or not the room is flooded with light, even daylight, the UV
emissions present are negligible at best. When a consumer/retailer is only a
few inches from a glass windowpane (even plain untreated glass) the UV is
greatly diminished; when only a few inches away from a UV-emitting light
source, the same is true.
And
last, but not least, another factor that can't be ignored is that more and
more homes and offices are moving away from fluorescent bulbs to LED lighting,
which contains insufficient UV emission to stimulate any fluorescent reaction
in any stone. This means that any
rationale that some have used at one time – however flawed* – to justify allowing UV emissions in a diamond-grading
light source will soon be obsolete.
* When indoor
lighting moved from incandescent to fluorescent lighting, some believed that
the fluorescent lighting present in any indoor environments containing them
were sufficient to stimulate a fluorescent reaction in any diamond that
fluoresces. Thus, any diamond that fluoresced blue, would look whiter, and any
that fluoresced yellow would look more yellow. Thus, it was thought that
allowing UV emissions in the diamond-grading lighting units would be more representative
of the color that would be seen most often. This flawed logic resulted from a
lack of knowledge pertaining to the physics of light.
