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Diamond cut gemstones


#1

Some mention was made about aquamarine and the term diamond cut.
Diamond cut refers to a pattern of cutting a gem with a round
outline, It has eight main pavillion facets that go from the girdle
to the pavillion, each pavillion main has two pavillion girdle
facets, on the crown is eight mains, each crown main has two crown
girdle facets, eight star facets, and a table facet, resulting in a
gem that has a total of 58 facets, what we call a standard round
brilliant, also known as diamond cut. There are diamond cut rubies,
sapphires, garnets, emeralds, ect


#2

Would this be full faceted as well?

Eva


#3
...a gem that has a total of 58 facets, what we call a standard
round brilliant, also known as diamond cut. There are diamond cut
rubies, sapphires, garnets, emeralds, ect 

Within these parameters, there is no reason the stone can’t be cut
with its own appropriate angles rather than those for diamond… but
that doesn’t mean it is, of course.

My own personal peeve is stones that are cut with a big rounded
belly to make them weigh more, at the sacrifice of brilliance, plus
they are much harder to set since they tend to slide around-- like
setting a marble with a faceted top. But then, I am not expert at
setting…

Noel


#4
Within these parameters, there is no reason the stone can't be cut
with its own appropriate angles rather than those for diamond...
but that doesn't mean it is, of course.

The term diamond cut refers to a pattern of cutting, and has nothing
to do with the angles that are used. Theoretically a gem should have
pavillion facets at the angles at which there is no light leakage,
and that varies with the refractive index of the material. Assumption
would be that diamonds are cut with correct pavillion angles, and
they
are not always, and in fact vary quite a bit from not at all, to
almost, to ideal proportions. There is a great little plastic viewer
that is from www.ideal-scope.com that is easy for anyone to use, and
the outside of the box has examples of poor, fair, and excellent
cutting of pavillion facets for diamonds. Occasionally I buy or trade
for diamonds from the public to use f= or replacement for repair
work.
When I looked at what I collected with this scope, all of the
diamonds
were very poorly cut, meaning a lot of light leakage, light not
returned to the eye of the beholder. These diamonds did not look that
bad to me, and I was surprised at how good they looked in spite of
how poorly they were cut

Generally I am matching the quality of the gem I am replacing to what
is already set. The big difference is when the diamond is.25 or
larger. There is a dramatic visual difference, but only when two
diamonds are compared side by side. A poorly cut diamond can look
pretty good, but compared to a well cut diamond there is a big
difference. If you are picking a diamond from a parcel, and they are
cost the same, you get more value for your money and you give your
custoomer more value for their money. The importance of this is that
when buying diamonds or colored gems, the customer generally has no
idea of the difference between poor cutting and good cutting, and
this is where your knowledge can make a big difference, and educating
your customer pays you back big time. The other main issue with how
diamonds are cut is that the top facet, or table, is where the white
light is returned to the eye, the crown facets are where the
dispersion, all the pretty colors, come from. How the crown is cut
determines the balance of white light and dispersion. Too big of a
table, less dispersion, less attractive.

Richard Hart


#5

When I lived in the SF bay area I bought stones from a firm on Post
Street in SF. They sold colored stones that were refered to as
diamond cut. As I understood it, the stones were cut with the same
care as diamonds; not as many “native cut” stones are cut with
"bellys" and strange pavillion angles. Of course one paid a premium
for these stones.

K Kelly


#6

Yeah, I know what you mean. You almost need a ball bur that’s had
the top of it cut off to set them. (Or bottom…depending how you’re
looking at it)

Stanley Bright


#7
Yeah, I know what you mean. You almost need a ball bur that's had
the top of it cut off to set them. (Or bottom..depending how
you're looking at it) 

I assume this is in response to my rant about bellied stones…

My solution has been to cut the seat with a bud bur.

And, by the way, yesterday, just for fun, I decided to try flush
setting a trilliant stone (a 4.3mm colorless topaz). I did it–
though not well. But it’s in there, which is fine for a first try,
especially without instruction other than my written notes from
Blaine Lewis’ quick verbal description a couple years ago. I just
put it in silver, as I correctly anticipated that it wouldn’t look
fabulous. Actually, the front’s not bad, but the back is a mess. It
isn’t easy to saw out a triangular hole with sloping sides in a
ring, without hacking up the back or the shank! Kudos to those who
do this kind of work all the time, in not much time and for not much
money!

Noel


#8
It isn't easy to saw out a triangular hole with sloping sides
in a ring, without hacking up the back or the shank! Kudos to those
who do this kind of work all the time, in not much time and for not
much money! 

Noel, whenever you have to fit a stone to a hole, especially flush
settings it takes time. You can go faster as you get more experience,
but the technique will be essentially the same. You might try
securing the piece well, and work away with a graver too. That can
save time. Be a bit more gentle with the saw if I can add that. You
should be able to keep the bottom of the shank in tact. What I mean
to say is that this kind of work always takes time. Mind, it is
easier to embed the shape into wax if you have that option. The
poorer the cut the more work you have to do and that equates to the
cheaper the stone the more work (a lot more) and in a lot of cases it
is never going to worth the while no matter how good you are fitting
odd shaped stones, flush set…

Phillip