there is a saying in the UK that you cannot polish a turd
I am not sure of the definitions used in the jewelry industry for
“polish”, but it has been my experience that anything can be made
shiny if one has enough time to experiment with abrasive
types,application medium (carrier and lubricant), time and pressure.
I am amazed. Where can I buy a carat of diamond dust for $7.50?
At any lapidary supply. But don’t expect glittter. At that size, it
will be a gray powder. $7.50/ct is way too much, though. You should
pay anywhere from $2-$3/ct, depending on quantity.
Yes I think so but I was amazed by the post yesterday on how “dirt
cheap” diamond grit is so I was just wondering if the bang for the
buck might be quite high if they are set in the right medium, eg a
plastic-like bead.
A swarm of thousands of pieces of grit would in theory reflect light
off each other and pass light through each other and act like the
faceted, cut stones in that respect. But optics may say otherwise.
This is also a reason I posted on “quantum diamonds”, ie to see if
there is any practical jewelry aspect in it.
I am amazed. Where can I buy a carat of diamond dust for $7.50?
Has anybody tested it out to see what kind of glitter it gives as a
surface coating (eg embedded in plastic)?
First, diamond grit as small as micron size is readily available
from many suppliers at $1.00 per carat or even less, depending on
quantity. This is probably mostly synthetic diamond. 50 years ago the
same grit cost $4.00 per carat, which would be more like $40.00 in
today’s dollars. Huge difference, no?
“Glitter” depends on both surface luster and optical effects of
refraction and reflection from within the stone. Both of these relate
to the Index of Refraction (IR) of the material, also whether the
interaction is taking place in air or in some other substance. If the
imbedding substance has an IR near that of the crystal, the latter
seems to disappear. So imbedding diamond in anything would tend to
diminish any surface luster.
A question has been asked, "what would happen if diamond powder were
imbedded in plastic?
This has actually been done- look at a mylar polishing film. The
diamond just looks grayish or white, just like the diamond powder
itself. A good example of what happens when a high IR is reduced to a
powder may be seen in titanium dioxide used as a pigment. A crystal
of the mineral rutile may be pale yellow to red to nearly black.
Finely ground it is pure white.
The finish on these polished spheres is applied to pottery before
firing and is usually referred to as burnishing rather than
polishing. yes, you can burnish metals and in both cases it is a
form of plastic deformation. The soil and pottery burnishing rely on
removing water from the body, normally by way of the heat of ones
hands to get to a point where the clay has reached its plastic
limits and then rubbing so causing the alignment and compression of
the clay minerals with little in the way of porosity which would be
much in evidence in the uncompressed material. This is changing the
fabric of the original material quite markedly. You can also freeze
dry a sample of dung and impregnate it with a suitable material to
make it stable, or use osmosis to replace the water content. No doubt
you can polish coprolites (fossilised excrement) using rechniques
used for polishing other rocks but strictly speaking all of these
methods require some alteration of the original material. So, despite
the examples shown I believe that the original quote stands.