Ultraviolet light and pearls

Does anyone have knowledge of the results of ultraviolet light on
pearls?

In attempting to verify natural vs. cultured origin of 4mm pearls,
white to greyish in color, with an iridescence. i placed them under
uv light and they did not take on the "ghost like white of pearls
that are known to be cultured.

Could this be indicative of natural pearls or salt water vs fresh
water, or natural vs.cultured? any imput would be a help.

I do not have ready access to xray facilities, and they are not
drilled to accomidate examination of the drill hole with a
microscope.

Thanks
Irwin Franco

Have always used the ‘On the teeth’ method of id’ing pearls… If it
scrapes across the teeth as somewhat ruff then is is a pearl… if
soomth it is not a pearl… anyone else use this? for quick id?? Jim

I use that system, but when doing so I also test with my tongue,
while trying to remember how the inside of a shell found on the beach
tasted like when I was a kid. The heat properties of a real
pearl(freshwater or cultured from an oyster) are distinctly different
from the usual artificial pearl. The latter seems painted in some
way, and quickly warms to the temperature of one’s mouth. Real
pearls seem colder, and absorb heat from the tongue. A few “taste
comparisons” with artificial and real pearls will teach anyone the
trick promptly. I have never tried to distinguish the fake pearls
composed of ground up shells (?) from real ones this way.

Dian Deevey

Dear Jim

     Have always used the 'On the teeth' method of id'ing
pearls... If it scrapes across the teeth as somewhat ruff then is
is a pearl... if soomth it is not a pearl... 

Yes I always use this if in doubt. The only problem is one cannot
tell how thick the layer of nacre is. Anybody out there with other /
better suggestions. Regards Niels Lovschal