Welcome back everybody this is Gemology for Schmucks. I'm your host Peter Nelson
and I'm going to tell you everything you need to know about the anatomy of
gemstones today. All right now why is the anatomy of a gemstone important. Is it
just some more vocabulary you can jot down in your notebook that way you have
something cool to show off at a party. No we're not that geeky. We are... we are that
geeky. However this is more important than that. The reason that the anatomy of
a gemstone is important is when you're looking at a gemstone whether it's
online or in person this gives you the terminology that you need in order to
communicate those things, things you might notice, to the gem dealer: the
person who owns it. So if you can't communicate using the proper words, "you
know... the top part of the stone or the bottom part of the stone... people think
you look like a schmuck. So what we're gonna do today is drive out that shame
and we're gonna give you the tools you need to talk about this properly.
So let's get into it. As I move this stone around you can see
all sorts of geometric shapes at the bottom of the stone. These shapes are all
caused by something called facets. So any flat part of the stone you can see
there's kind of an octagon on top of the stone and there's lots and lots and lots
of tiny flat areas. These are all called facets the most obvious part of a stone
perhaps is this wide part it's very important when you're thinking about
setting it in jewelry because that's the area that's gonna get a hug from the
jewelry. It's whats gonna hold it up in your ring or on your pendant so this wide
part right here this line that goes right across it's called the girdle. You
can think of those old guys that come and move your your couch and your piano
from your house to another house. You might see them strap a belt around their
back so they don't throw their back out. That's also called a girdle
what is this flat plane at the top now if we look at the gemstone like this you
can see that it's parallel with the girdle and that's what we call the table
this area that is on top of the stone this one facet right here is called a
table. Now everything from the girdle up is called the crown. The crown sits on
your head right so we have a girdle. Everything above that is the crown and
this one facet right in the middle here is called the
table now what is below the girdle Everything from this line down is called
the pavilion so if we turn it pavilion side up you can see that it comes to a
point. Now if you've ever seen anything medieval... if you've seen the tents that
kings and queens stay in when they go on a hunting party or they go to war or
something like that you'll see a tent with a large spike in the middle that
also traditionally was called a pavilion so we've got the pavilion leading up to
this point right here as I turn the stone around it's only one point that
point is called the culet. Here we have a comically large piece of topaz and you
can see this is very similar to the previous gem, the piece of Kunzite
and you'll see that there is a table on top you see that the crown is right here
and there's a girdle right here and lots and lots of facets everywhere on the
pavilion but what's the main difference if you look down here at the pavilion
you'll see that it's not exactly a point it's in fact a long line this is what we
call a keel line so if you don't have a culet. No point. It's not a singular point.
From this direction it's a point, but from this direction it's a line. This is
a keel line just like on a ship so in a ship you've got a rudder at the back
which is a board that steers the ship you'll see that there's a long board in
the middle that keeps the ship going straight in the water that's called the
keel, so here we've got a keel line instead of a culet. On this piece of
tourmaline you'll see the exact same. From one direction it looks like a point,
but from the other direction it's a long line. This is again a keel line. You'll
see in front of me that we've got two more gemstones that are not the same
type of shapes that we were seeing before with lots of flat facets this
type of cutting is what's called a cabochon the parts of a cabochon are a
bit different from faceted material. It still has a girdle down here at the base
but everything above that girdle is just a dome for the most part oftentimes
you'll see below the girdle there's also other material
This isn't perfectly flat. With more expensive gemstones that area can
be quite a bit larger. But when you're buying cabochons, do look at the area
below the girdle. If it's too large, that's not weight that you're getting to
see but it is weight that you're going to be paying for. So especially with
something like a star sapphire, you have to be careful that maybe 30 percent
under the girdle is okay. Maybe that area that weight is important to keep the
star in the stone, but if it's more than 30 percent below the girdle, you're just
paying for weight that you don't get to see. So again you can see that the base
is not perfectly flat and that's okay The advantages of not having a perfectly
flat base are that it actually makes your stone a bit tougher. If the angles
on this base aren't perfectly flat they may be able to take more glancing blows
without chipping so a little bit of a round base is not a problem. So a
cabochon really is just domed cutting it's a polished gemstone that's in a
dome before gemstones are polished or cut and faceted and all of these things
or turned into a cabochon, you have them in the form that you see in front of us
right now. Now these could be pebbles that you find in a river these could be
shards of a crystal that are clipped off this is what sapphire actually looks
like before it's cut, sometimes, and right here we have some agate. You can kind of
see the growth bands right in through here. This is what agate looks like. It's
just a shard and then right here we have... I believe this is fluorite. Anyhow all of
these pieces are what we call 'rough'. So gemstone rough is really just any gem
material before it is cut. So what else is out there in the world of gemstones
you can see in front of me there's this piece that we call a specimen. Now a
specimen is gem material on top of or in its mother rock. So this area right here
is the crystal that they would actually use
it's very lightly colored you can see but the crystal growth is very very
distinct you can see that it has a definite geometric shape and a gem
material on top of the mother rock like this is worth quite a bit to some people
if you get a specimen like this with many different crystals and the crystals
come to their natural end point that's what's called terminated crystals so
over here in this piece of quartz it's actually got some petroleum and carbon
in it these points these are not faceted this is actually naturally how the
crystal grows and this is what's called a terminated crystal. So if you have a
specimen on mother rock, that's also terminated, that adds to the value of the
specime. So this is a piece of Kunzite rough. It's actually interestingly quite
thin. You've seen a lot of big stones right, But some of these stones uncut
though they are, still only grow in long thin pieces like this. So this edge right
here this is uncut by man. This is just how the stone comes out of the earth and
this is also a terminated stone. And this right here is a fluorite specimen. You
can see that the crystals are in these interesting square shapes all over the
specimen and as we turn the specimen over its got mother rock and some mud
and sand and all these other things. Isnt that nice... All right everybody that's all
for Gemology for Schmucks. Once again my name is Peter Nelson. Thanks for joining
me today as we talked about the anatomy of a gemstone and I hope that this will
help you as you go and you start to browse online or you talk with gem
dealers about their stones that way you know clearly what areas they're talking
about and you don't have to just go yeah I mean it's it's like if I were to start
talking about cars and yeah the carburetor... My brother looks over at me
and says they haven't put those in cars for decades....oooo the shame... but no no no today
we're pushing out that shame now you know. You'll be accountable for it next
time I'm gonna start throwing out words like pavillion and keel line and a table
and all of these things. Don't forget your crown! Everybody needs a crown...
...especially me... King of Schmucks . Goodbye
you