The first 'c' is Cut


 Let's

single cut

look at CUT.


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CUT, especially in round stones.


If you look at pictures of the pyramids at Giza in Egypt, you will have a pretty fair idea of what a diamond crystal will look like under an electron microscope.  Layers are arranged in planes in a square pattern.  If some guy with a pry bar went up on the sides of the pyramid, he could easily separate the stones.

  

So, this cleaving of the stone was a good start for the discovery of how to cut the stones.  Unfortunately, this easy cleavage is also a great downfall, as all it takes is a good rap on the end of the grain to break a diamond.  Great care must be taken to make sure the edges of the stone are protected so it cannot be easily hit. Big stones become very vulnerable as a result.  Don't wear your 30 carat emerald cut stone working on the roof or shoeing the horse.  Just a grazing hit on a metal or stone surface can shatter the stone or at least split or chip it.


This means that if you have a good-sized stone in your ring it is wise to do more than four prongs to help protect the edge of the stone.  The larger the stone, the more the curve of the stone protrudes beyond the prongs.  As much as I like emerald cut stones and ovals, I do not know what people are thinking.  Those stones have broad unprotected sides.  


You will notice that a man's ring will almost always be either recessed slightly into the gold work to where the prongs are or set in a collet that wraps around the edge of the stone.  


This harks back to a time when a wealthy woman might comb her hair as the most strenuous activity of the day.  Times have changed and women have taken their rightful place in the world which includes activities that can shatter her diamonds during daily activity. 


They eventually found that though diamonds were hard, they could be ground to shape fairly easily by working the angle of the grain of one stone against that grain on another or even with softer substances.


A sharp blade can be laid along the grain of a stone and a quick strike can split it along the grain like using an axe on a log.  An experienced person can do this rather easily, an inexperienced person can turn a stone to crumbs with one strike.


The largest cut stone in the world was the Cullinan diamond. (There is actually a larger stone, but it is a black or "carbonato" diamond found in Brazil) The Cullinan was given to the British royal family.  The story goes that a Dutch diamond cutting master was given the stone to study for months and the time finally came to split it the first time.  He placed the blade, raised the striker and hit the blade.  The stone promptly split in two as planned.  The man who cut it promptly fainted dead away.  The many stones that were cut from the Cullinan diamond pepper the British Crown Jewels and also the personal possessions of the monarch.


 Later, they found that simple disks of metal could be charged with diamond powder on the rim and would cut or wear through a solid stone in angles other than with the grain.


 A horizontal disk could have the flat surface charged with diamond powder in oil and they could wear away at the stone. Using finer and finer powder they could refine the shape and polish the flat surfaces.


Originally the diamond crystals could have one of the pyramid points cleaved off and polished and then facets (flat faces) could be ground from the rough, fairly regular crystal to make a rather squarish (sort of like a greatly overstuffed square cushion) shaped stone that followed the general shape of the crystal.  These were called OLD MINE CUT and cushion stones.  These could be fairly even and approach the dimensions of a modern stone or they could be more primitive, sort of like a lumpy, sparkly ball.  Take a look at a dodecahedron in your old geometry book and you will get a general idea of the appearance of some very early cut stones.

Old mine cut


Over time, crystals were rounded and refined much more and resulted in a similar cut but almost round looking at them from the top. From the side they looked like a blunt cone pointing down and a cut-short cone pointing up(truncated) on the top. These were OLD EUROPEAN cuts.  As time went on, they were refined more and more to make more regular and well thought out cuts and eventually they became the 58 facet Modern Brilliant.

Old European Cut


Newer cuts are now popular but all of them are nearly impossible to describe in the text.  I will try to post photo examples.


For a long time, old stones tended to be a little less valuable because everyone wanted the new cuts.  When old stones were evaluated, most often the evaluation was based on the size of stone that could be recut out of it...minus the cost of recutting, of course.


This is a little less so now as many people have learned to appreciate the softer glow of the old stones compared to the colder glitter of the new ones.

Rose cut...a good one


Other early cuts were just a few facets that could be produced quite quickly and cheaply.  These are still produced for cheaper reproduction jewelry. They sparkle, but they cannot produce the rainbow of reflection and color present in a modern stone.  They are called Rose Cuts and are usually flat on the back.   A similar cut is called Senaille and are usually rather erratic in shape but otherwise you could probably just lump them in with rose cut stones. I suppose Senaille sounds more exotic than diamond chips or rose cut stones.

Brilliant cut


The modern stones are cut at very exact angles that allow the light to enter the stone at any angle. Bouncing around in the many mirror-like facets of the stone which is cut to very exact angles and dimensions.  The white light is broken up like in a prism and reflected back mostly out of the top of the stone to your eye with many rainbow colors.  The idea is to cut the stone so that light will bounce around inside and out of the top rather than reflect out of the stone on the back or sides.


We could discuss the fact that the side profile of the stone is cut at about a 75-degree angle and the top half and bottom half of the stone should be certain proportions; but really only a handful of people could possibly look at a stone and notice these correct dimensions. In the very roughest terms, you might notice that the top part of the stone is about 1/3 and the bottom half of the stone as about 2/3 of the height.

It is much more exact than that and requires much more exact calculations to get a truly well-cut stone, but the untrained eye may see that much.


Let's just look at a few basics.


The top octagonal facet that is most obvious to the eye is called the table.


The upper part of the stone is called the crown.


A line around the outer edge of the stone where the top and bottom meet can be opaque white and either rough like sandpaper or faceted like the rest of the stone.  This is called the girdle.


The bottom (around 2/3) of the stone is called the pavilion and tapers down from the girdle to the pointed bottom of the stone. 


The point on the bottom is prone to chipping, so it is usually cut into a flat facet called the culet. (Facet just means face)  

The culet is supposed to be nearly invisible to the eye but may practically range from a true point on the bottom of the stone to a rather obvious octagon visible in the bottom of the stone.  At its worst it can look like a nearly dead black spot in the stone.


There is almost no way for a layman to tell if a round stone is cut correctly by just looking at it, and with many stones in a piece of jewelry it is impractical to study all these stones to be sure.


There is one quick trick to help judge with the naked eye.  The table is an octagon.  It should look absolutely even and regular.  


Radiating out from the flat sides of the octagon are triangular facets that are called star facets.  You can tell why as the top of the stone looks rather like an eight-pointed star.  Here is what to look for:


  If the crown of the stone is too high or thick, the star points will look rather long and pointy.  If it is too shallow a cut, the points of the star will look rather short or squat.


The top of the stone looks rather like two squares superimposed on each other at 45-degree angles (see the illustration) making the octagon of the table. On closer examination, these two squares will not be made of sides that are quite straight.  A well-cut stone will have star facet sides that bow EVER SO SLIGHTLY out at the points. If the curve is pointing very strongly out, the stone is too tall.  If they bow inward or the line is straight, then the crown of the stone is too short.  The rest of the facets...well you are on your own.


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The bottom line, though, if you are looking at a number of stones, is that when you compare stones side by side, a well-cut stone will have an impressive play of sparkle and reflected color in the stone.  Poorly cut stones compared to the others may seem a bit dull and lacking in sparkle and color.  

Sales people usually display jewelry under very intense overhead lights to make them more attractive.  The funny thing is that diamonds in candlelight are absolutely beautiful.  

I once made up a wedding set of mixed antique stones that consisted of a tiara, earrings and necklace.  The best stones were two that I put in the earrings.  When the set is viewed as a group, your eyes are immediately drawn to the sparkle and fire of those two stones surrounded by all the others.




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The next component of the cut is the physical shape of the stone.


Also included here is the skill of the cutter of the stone.  A stone may be misshapen, the work may be skilled or shoddy.  Facets may meet properly at corners or not...The angles may be correct or not.  Also, the shapes discussed above affect the value of the stone.

The girdle of the stone can be rough ground, or it can be faceted.  The girdle may be thick or thin. A very thin girdle may be more prone to damage. A very thick girdle may contribute to a "too deep" stone and loss of brilliance.


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