I am Steve Moriarty I come to you from MoreGems.com online and we also have a
retail store in Crown Point Indiana (Moriarty's Gem Art) Today I want to talk to you about
cutting styles and what I use to determine how I'm going to cut a gem
many gems you can just take the piece of rough cut out what's bad and determine
what the biggest stone you can get out of it and go ahead and cut that other
gems is a different situation for instance tourmaline we have here a green
tourmaline it's a beautiful Bluegreen from Afghanistan the direction of
cutting for color is the a/b axis which is this direction this is the C axis and
if we look at it you can see there's some yellow coloration to it and often
the C axis is totally black so we want to cut on the a B axis for color and
we'll generally cut the ends of the stone very steep so that awkward yellowy
green color or the black does not come into the stone itself each tourmaline is
different this is pink tourmaline from Nigeria the best color is actually down
the C axis but because this is a fairly small stone the C axis direction you
would only get maybe three carats out of it or if you're lucky this direction you
get 6 carats but fortunately this material you can heat treat and this
direction that has a little bit of Brown to it currently will cut a nice pale
pink stone so we can also cut this on the a B axis and get a nice Jim barrels
generally always cut on the AB axis this aquamarine and emerald will be the same
situation where the best color will be on the a B axis not down the sea and
it's fortunate because of the large size you'll get out of this town much greater
on the a B axis and these are generally cut and emerald
cuts as the term lanes are just because of the crystal shape you'll get the best
yield from an emerald cuts down so this is going to cut a long thin emerald cut
tanzanite a little different situation we have a trichroic gem and I'll try and
show you the three colors that are in tanzanite in the rough material the
colors are yellow purple and blue once it's heated the yellow will disappear so
let me try and show you the three colors are in this cone this is a dichroic film
so this is one direction of color keep in mind that the yellow that are in
these are are going to disappear when the gems ultimately done and the third
direction you get it straight for you
so that's the three directions of color some think that cutting on the blue
direction which would appear to you as the blue and yellow in this case is the
best it's it's nice to get it all blue stone because it is rare to get stones
that are strongly to the blue but the ultimate beauty of the stone in any
direction you cut it in my opinion you should just be cutting for size and not
from weight because it's expensive material and the size is important
zircons another stone that particularly the blues these this is a stone from
Tanzania that's a blues from Cambodia I'll have a
consideration and that's strong birefringence and what's strong
birefringence does is when you cut the gem if it's cut on off the optic axis
you can get what's called doubling and doubling is the back facets ideally each
facet each line where they meet will show up as one line but when you get
doubling you actually get two lines and what this does is make the gem look hazy
because of the multiple facet lines so it's a consideration and fascinating but
a piece like this there's only one direction to cut it otherwise you'll get
a very small gem so you take what you got you cut it you know for the best
clarity is another situation when you clean up what you can off a stone there
still may be inclusions in it and your concern will be getting the inclusions
as far out of the center table as possible the further out to the edge
under the crown facets the less the inclusions will be noticed and things
like fractures if you can get them vertical in the gem which meaning
perpendicular to the table they'll show up less and this is particularly true in
material like googly where they have needles that are all in one direction
they're just like needles in the stone and if you look at rubellite cut those
needles are perfectly perpendicular to the table and they're very difficult to
see even though they're me I'm going to be multiple needles and within the gem
and color is another consideration how deep the material is lighter gems you
can cut in almost any fashion and they can produce a beautiful gem cutting
round brilliance and light material producing a lot of brands you can do
pear shapes marquees things with long links the widths in light gems
whereas in dark gems like this material which is amethyst that comes from Rwanda
the very dark material and if you cut long length width lock air shapes and
marquees what's going to happen is the ends of the gel will be very dark so we
tend to want to cut squares and all cuts round brilliance and not cut too deep
because depth will accentuate the depth of the color and in dark material this
can just produce a black gem so in this material I've tended to cut
rounds and square cushions emerald cuts work timing
limiting the depth of the stone although this very dark material you can lighten
by heating so that does give you an option to cut other styles of cuts
although deep color in this material is what makes it so beautiful so just avoid
marquise pear shapes other gems that have issues would be sapphire this
material comes from Madagascar
it appears light color in the rough but what you find in sapphire is that it's
heavily colored zone so the zones form a hexagon shape within the gem and and
there can be just small sections of color and the goal for you is to either
put the color into the culet of the stone because I've seen stones from Sri
Lanka where only the qulet has color and if you face it up it shows a beautiful
blue color if you look at from the side you can see that the whole gym is
colorless except that to cue it so it's very
important where you put the color so you need to immerse this this gem and
identify just where the colors at and work to either get into culet or if it's
a wide enough band you can spread it across the whole crown of the stone and
it will spread through the rest of the gem even if that rest gem is colorless
emerald cuts and step cuts tend to deepen the color of a gem so if you want
it to look darker or richer color and those are cuts worth using deep cuts
like Portuguese cuts will also tend to accentuate color because of depth like
looking through water the deeper they look the darker the materials parent color
is so cutting a deep gem will accentuate the color but in dark gems it's probably
not what you want because you'll get over coloured stones brilliant cuts do
tend to lighten the color but it's a trade-off because the brilliance you get
can can be more important than how light the color is as we look at a diamond you
see that the brilliance is is what you're looking at not the color of the
stone but add a little color to it and round brilliance and square brilliance
can some of the most beautiful stones even
though they are deep color so it's a good trade-off cutting a good brilliant
gem that has one-to-one proportions if you had the opportunity so it's very
important to choose your rough wisely know what the limitations of the
particular rough is and if it has issues you just reject it and go on and try and
find something that'll not only give you a good yield, but that will give you good color
and a beautiful brilliance so I'm Steve Moriarty coming to you from MoreGems.com
and we thank you for watching.