gemstone flourescence

I like gems that "glow in low light", so would have some questions;

1. In which jewellery gemstone varieties is flourescence most common (I =
know
of diamond, corundum, flourite, sometimes topaz and amber)?
2. Can you detect flourescent gemstone with a naked eye with no special
light sources?
3. I heard that most flourescent gems are "hazy" - is that a rule (cause =
it
would mean, for example, that fire opal is often flourescent and I'm not
sure if it's ever)?

Thnx!

On Tue, 11 Oct 2005 19:32:27 -0700, in h=07=F5 "m4816k"
wrote:

I like gems that "glow in low light", so would have some questions;

I think you must mean "black light", or ultraviolet. Low light, meaning =
just
not much light, won't cause gems to glow, or much of anything else, other=
than
perhaps some romantic moods. What you're referring too, fluorescence, is=
a
reaction to ultraviolet light, which is high energy, but not visible to =
the eye.
Many materials react to it by absorbing it and radiating out that energy =
at some
lower wavelength, which then is visible light.=20

1. In which jewellery gemstone varieties is flourescence most common (I=
know
of diamond, corundum, flourite, sometimes topaz and amber)?

Hard to list, since so many gems sometimes fluoresce. There are many =
gems
where a small percentage of samples can be strongly fluorescent, while =
others
are not. Diamond is one of the most commonly used gems where the =
fluorescence
is specifically noted and even, sometimes, designed around. remember, =
though,
that it's not universal to all examples of a gem. Only some diamonds =
fluoresce,
and only a small proportion of those do it strongly enough to be =
dramatic, in,
say, the low level ultraviolet lights of a night club or the like. Many =
of the
gems that fluoresce visibly under gemological testing conditions (a U.V. =
light
source fairly close, with both long wave and short wave UV available), =
may not
be so obviously fluorescent in the long wave only, lower intensity =
environments
where the light is safe enough for human eyes over time to allow it's use=
(like
those night clubs, etc.) Diamond is one such gem that can be quite =
dramatic in
that environment, if it's strongly enough fluorescent. Some of the =
others are
not strong enough to be all that dramatic. One interesting one is flame =
fusion
type synthetic ruby, which glows red more strongly than the natural =
stones
(which may not fluoresce at all) A number of synthetic materials, =
including
some plastics are also very strongly fluorescent. And there's a whole =
class of
minerals, not otherwise used as gems, which are known as much for their
interesting fluorescence, as anything else.

2. Can you detect flourescent gemstone with a naked eye with no special
light sources?

You need to have a light source with at least some ultraviolet in it. =
Sunlight
fits, as do some ordinary fluorescent bulbs. In this lighting, which =
may or
may not be considered "special", you might be able to detect the =
fluorescence in
some strongly fluorescent gems. In some, the fluorescence affects the
appearance, but for you, the viewer, the effect can be just to make the =
color
look more intense than it would do in other light sources (synthetic ruby=
is
like this) Telling that it's actually fluorescence, takes at the least, =
very
strong light, and better, a true U.V. source of some sort. Diamonds, if
strongly fluorescent, tend to have a sort of greasy or hazy bluish tint =
to them
in sunlight or strong fluorescent lighting. But this sort of visibility=
is
actually somewhat unusual. With more fluorescent gems and materials, =
ordinary
light is bright enough that any fluorescent effects get overwhelmed by =
just the
ambient light, and you don't notice anything.

3. I heard that most flourescent gems are "hazy" - is that a rule =
(cause it
would mean, for example, that fire opal is often flourescent and I'm =
not
sure if it's ever)?

No, it's not a rule at all. Fluorescent diamonds can be quite clear and =
not
hazy at all. Only if they are brightly glowing, like a light blue, is =
the eye
aware that something is not normal with the stone. most diamonds that =
light up
nicely under a U.V. lamp are still not fluorescent enough for that hazy =
look to
show up in ordinary lighting. The only other gem I can think of where the
fluorescence is strong enough to show up in some normal lighting (needs =
very
bright light or sunlight) is the aformentioned ruby types, and in this =
case,
since the material is glowing red, to compliment it's color, there is not
conflict between the glow and the normal optics, so the stone still =
appears red,
just brighter. Now under actual U.V. sources, with subdued visible =
light, then
the fluorescence is ruby, or most other fluorescent stones, may appear =
hazy or
even semi opaque, since the whole mass of the stone is giving off light,
presenting a very different look from the normal optics of a facetted =
stone.
But even then, I'm not sure "hazy" is a good word for the effect. A lit =
light
bulb looks lit, not hazy, for example.

Peter

On Wed, 12 Oct 2005 03:00:12 GMT, "Peter W.. Rowe,"
wrote:

On Tue, 11 Oct 2005 19:32:27 -0700, in h=07=F5 "m4816k"
wrote:

I like gems that "glow in low light", so would have some questions;

I think you must mean "black light", or ultraviolet. Low light, meaning=
just
not much light, won't cause gems to glow, or much of anything else, =
other than
perhaps some romantic moods. What you're referring too, fluorescence, =
is a
reaction to ultraviolet light, which is high energy, but not visible to =
the eye.
Many materials react to it by absorbing it and radiating out that energy=
at some
lower wavelength, which then is visible light.=20

snip

I have some confusion here. If the OP really means gems that "glow in
low light", the reference would be to phosphorescence, not to
fluorescence. The phosphorescent minerals I'm familiar with may be
pretty, and could be polished into use as jewelry - e.g., petrified
wood - but isn't usually referred to as a gem. Are there gems, Peter,
that phosphoresce?

Blessed be, for sure...

On , in T=07=F5 Jim wrote:

Are there gems, Peter,
that phosphoresce?

A few. It's rare. Diamonds are one such, though again, it's rare and =
unusual.
If I recall it right, limited to specific types, not just random samples.=
Of
the materials I've heard of which phosphoresce, it's also generally not
something strong, or especially long lasting. It's gemologically =
significant
when a gem visibly phosphoresces in a dark environment after light or UV =
are
turned off, but not so significant to any use in jewelry if the glow only=
lasts
a few seconds or is only visible in very darkened conditions. I'm not =
aware of
any gem materials that phosphoresce strongly enough, or persistantly long
enough, as to have significant aesthetic appeal in jewelry use, or to =
the
really quite amazing degree of some of the materials used for that =
reason, such
as the "glow in the dark" materials in watch faces and hands (other than =
the old
style radium types), or in various plastic materials that do the same. =
There
may be some gem materials, especially some of the "mineral community" =
minerals
that might marginally be used as cabochon type gems in a pinch, that do =
it, but
I'm not aware of any specific ones. You might try asking in one of the =
science
oriented newsgroups where you might find a geologist or mineralogist or
something. =20

Peter