Saturday, 26 November 2016

How to set diamond cutting tange / tools?

Setting your diamond cutting tange

After you have set your diamond cutting bench and added your correct lighting and acquired your tools. You will need to set your tools correctly in order to polish your diamonds with accuracy. 

Understand how a diamond cuts!

In order to understand how a diamond cuts you will need to visualize a polished diamond in a rough diamond. A typical Octahedron Diamond is divided into 2 main parts namely the 4 grains and the 4 faces (Octahedron faces) totaling 8 main facets on a Round Brilliant diamond.
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Diamond grains
A CVD Diamond (Chemical Vapor Deposition or lab-grown diamond) has a similar pattern - Although not clearly defined by grains one can still predict its cutting directions. CVD's are usually grown in blocks and one can visualize its grains and faces.

CVD Diamond polishing, diamond cutting a CVD diamond, chemical vapor deposition diamond

The cutting directions of a diamond.

A diamond will only cut from right to left (when viewed) and left to right on a wheel.
Diamond cutting grains, diamond cutting directions, diamond polishing grains
Rough diamond cutting grains
We can now see how the lines on the facets will run - from right to left against each grain. The minute you cross over the middle of a grain you the direction will change.
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Rough diamond cutting grains
A basic round brilliant diamond has 8 main facets divided into what is known as " 4 Corners" and "4 Pavilions. The reason for this is that the 4 corners run in a the same direction (Right-in) while the 4 pavilions will run "Right out" always against the grain from right to left (when viewed)
4 Pavilions and 4 corners on a diamond
4 Corners and 4 pavilions on a diamond
diamond cutting grains, diamond cutting grain directions, diamond grains, diamond polishing
diamond cutting directions on 8 main round brilliant facets

The diamond cutting tool compass / grain directions. 

To further understand the grain directions of a diamond you need to understand how the diamond cutting tool operates. All diamond cutting tools has a rotating head. This head can rotate 360 degrees. To simplify this we added names to the main directions as most facets on a diamond will run in one of these main diamond cutting directions.
Diamond cutting directions, diamond cutting tools, understand a diamond cutting tool
Diamond cutting tool directions
Currently in the picture above the head is in the "Right out position" or facing North East. On a typical round brilliant diamond the 4 bottom corners will run in the "Right in" position while the 4 pavilions will run in the "Right out" position. As you gain more experience you will begin to find cutting directions more easily.

Grains on Fancy Cut Diamonds. 

On the sqaure fancy cut diamonds we will have the following main grain directions.

Leveling your diamond cutting tool.

Because facets run in different directions the tools head will rotate. The key here is to ensure that every facet is similar to  the next facet when you change direction. A tool that is not level will begin a facet slightly left, right, up or down every time you change direction. This will cause the facets to differ and mess with your symmetry. You want facets that is equal in depth and width.

In order to do this you need to ensure your tool is level. The modern way of doing this is to buy a clever tool that is designed to ensure your tools remain level and facets similar - The Morgana - This tool is available at http://www.hrdantwerp.com/en/product/morgana.
Avalon Plus, diamond cutting tools, diamond cutting level tang, tang level diamond cutting
Morgana tool level

What can the Morgana do?

Tang plate alignment set

The tang plate alignment set is a set of tools that will help the polisher to bring the tang plate on the same water level and in the same plane as the polishing wheel (the scaife). It is additional to the basic unit, which requires perfect alignment of the tang plate.
  • Control the flatness of the scaife
  • Level tang plate and scaife
  • Adjust scaife height
  • Check overall alignment of tang plate and scaife
  • Calibrate all polishing benches

Morgana helps the polisher to:

  • Align the tang plate(s) on the mill according to the scaife
  • Align facets to the scaife
  • Align the grain axis perpendicular to the scaife
  • Tilt the facet very accurately in a predetermined angle
  • Check the setting of the stone in the tang
  • Check the angular scale of the tang

Multiple advantages:

  • Easy to use
  • No size limits
  • Quick procedures
  • Prepare benches and tangs in no time

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Saturday, 19 November 2016

Setting up a diamond cutting bench

Setting up your diamond cutting bench / factory.


Diamond cutting is unlike any other gem cutting and requires specialized equipment in order for you to cut / polish diamonds. One of the first things you will need to cut diamonds is a diamond cutting bench also known as a diamond cutting mill.
diamond cutting bench, diamond cutting mill, diamond polishing bench, diamond polishing mill


There are many different companies that offer different styles of benches although they all share the same basic essentials for diamond processing. A diamond cutting bench is actually a very basic concept consisting of 4 adjustable legs (for leveling) a flat LEVEL surface (that is resistant to wear and tear)and tool guides. Some benches have additional tool guides with adjustable bases that ensure further leveling. This is however not essential if your main bench has a flat level surface.
What is essential is to have a very secure and vibration free diamond cutting bench as any vibrations from the diamond cutting wheel back to the diamond can cause severe damage.

It is also essential to have your diamond cutting bench level

diamond polishing bench, diamond cutting mill, diamond cutting bench
Ensuring your diamond cutting bench is level
 

What motors are used on a diamond cutting bench?

There are several different motors on the market but the general consensus is that the Coborn motor is still the finest.  The ideal speed of a motor should be around 2500 rpm. You do get speed adjusters that are very handy at times. For more information on the Coborn motor see. http://www.coborn.com/productSKSeries.php
diamond cutting bench, diamond cutting motor, coborn motor for diamond cutting
Coborn Motor for diamond cutting bench


Diamond cutting wheel (scaife)
The final part of the bench is  the diamond scaife(diamond cutting wheel). It is essential to have the wheel level on all sides. As this ensures proper faceting techniques. 
diamond cutting wheel, diamond cutting scaife, diamond polishing scaife, diamond polishing wheel
Diamond cutting wheel


What is the best lighting for a diamond cutting bench / factory?
A diamond factory should be well lit as facets are small and polishing lines difficult to see without the correct lighting. For more on the proper lighting see my other blog on lighting.


Where can you buy diamond cutting benches?


Understanding the Shape of a diamond | Diamond shapes



Understanding diamond shapes.

It is essential for the diamond dealer to know the difference between the shape and the cut of a diamond as this is often a confusing subject.  The cut of a diamond refers to the diamonds angels and proportions while the shape of a diamond refers to the overall shape of the diamond e.g. Pear shape diamond, Oval shape diamond etc.  Diamond shapes are still however referred to and certified as Oval Cuts or Pear Cut diamonds even though there is a distinct difference. 

Why is it then essential to know the difference between the shape and the cut of a diamond?

When one wants to improve or re-cut diamonds you need to know exactly what part of the diamond will need re-cutting. Usually when diamond cutters alter the shape of a diamond they will additionally have to adjust the cut (angles and proportions) to match the shape of the diamond. The same is not always true for the cut of a diamond.  A diamond cutter won’t necessarily have to alter the shape of the diamond when he or she corrects the cut of the diamond. The shape of a diamond will affect the cut of the diamond as every shape diamond has its own unique angles and proportions.

Alternative cuts within a shape of a diamond

It’s important to note that within a particular shape of diamond one can find alternative cuts for example the Oval diamond can have 4, 6 or 8 main facets. The Oval is also very popular in the off-set cut (crown and pavilion meet in the middle instead of on the lines).

diamond shapes, diamond cut, differnt diamond shapes
Different cuts within a Oval Shape diamond.


This could be of importance - depending on what your company or brand is aiming to market. 

Why are certain shapes or cuts not noted on diamond certificates?

Certain shapes of diamond are registered trade marks for example the Radiant and the Asscher Cuts and therefore laboratories won’t add these terms to the certificates unless its sent in by the registered trade mark owners for example The Royal Asscher Company.  Although we refer to diamonds cut into the Asscher shape / Cut the certificate will usually state otherwise for example the Asscher cut will simple say “Square Emerald Cut”
It is extremely critical not to misrepresent the shape of the diamond to clients as this could jeopardize your brands reputation in the long run. I believe it is only a matter of time before we hear of a few lawsuits regarding the misrepresentation of diamond cuts to clients.


radiat cut, diamond shapes, diamond cut, diamond polishing
The Radiant Cut  / Shape is a trademark

What are the most popular diamonds shapes?

Round Brilliant
Princess
Oval
Pear
Marquise
Cushion
Asscher
Emerald
Heart
Radiant
Trilliant
Baguette


Top 8 branded diamond shapes
Although I only list 8 brands some of these companies have more than one brand available.
1.       Asscher - www.royalasscher.com
2.       Radiant - www.radiantcut.com
3.       Sirius Starwww.embeediatech.ca
4.       Biro 88 - www.biro88.com
5.       Tycoon - www.tycooncut.com
6.       Eighty-Eight - www.88cut.com
7.       Flanders - www.flanders-cuts.com
8.       Crisscut - www.christopherdesigns.com



Sunday, 13 November 2016

Natural vs. Lab grown diamonds | Whats the differnce between Lab grown and natural diamonds?


Natural diamonds vs. Laboratory grown diamonds

A synthetic diamond (also known as an artificial diamond, cultured diamond, or cultivated diamond) is diamond produced in an artificial process.  Although they are produced in a laboratory their chemical and optical properties are similar to natural diamonds.  In the U.S., the Federal Trade Commission has indicated that the alternative terms laboratory-grown, laboratory-created, and [manufacturer-name]-created "would more clearly communicate the nature of the stone" and should be clearly indicated on diamond certificates. This has led to several new terms used for laboratory grown diamonds – and are commonly known as Lab-diamonds or Lab-grown diamonds.

Master diamond cutter Conrad Kruger, diamond cutting, lab grown diamonds
A lab-grown diamonds being cut

What is the difference between a diamond simulation and a diamond?

Lab-grown diamonds should not be confused with a diamond simulants for example a cubic zirconia that does not have similar properties to natural diamonds.

What are the most popular methods to grow a diamond in a lab?

The two most popular methods for creating diamonds are;

  1. HTHP – High Temperature High Pressure process
  2. CVD – Diamonds (Chemical Vapor Deposition) process

Do lab- grown diamonds differ from natural diamonds?

In the HTHP process nickel, cobalt or iron is often added and this (in my experience polishing them) has made some HTHP diamonds magnetic (affecting the electronic properties of the diamond).  Not only are these diamonds magnetic they seem softer and break or chip far than their CVD counterparts.
CVD – Diamonds (in my personal experience) are extremely durable and superior in hardness and thermal conductivity than natural diamonds or HTHP diamonds.  

How is the clarity and colors of Lab-grown diamonds affected?

HTHP Diamonds.
In HPHT diamonds - clear white, yellow, brown, blue, green and orange diamonds can be manufactured. When copper, nickel or iron is added to the growth process you may find small metal impurities in the diamond. The color of the diamond can be significantly affected by the size and metal used in the growth process of the HTHP diamond. The HTHP process can be used to enhance the color of a diamond significantly. 

CVD  Diamonds.
During the CVD process polycrystalline forms inside and outside the diamond – black layers or sports that looks very similar to natural carbon impurities. In some cases, during the polishing processes the polycrystalline can be removed totally (IF – Internally Flawless). While in more extreme cases the polycrystalline can form large clouds within the diamonds. Identified as a straight line clouds  as its forms between two growth layers. In non-severe cases small traces of polycrystalline may remain within the diamond that looks very similar to a natural black carbon impurity. CVD diamonds often have a grayish overtone but its color can be improved through the HTHP process. 
CVD Chemical vapor deposition diamond, Lab-grown diamond, CVD diamond
A CVD (Chemical Vapor Deposition rough diamond )


Lab grown polished diamond, cvd diamond, oval polished diamond, diamond cutting
A CVD Diamond polished

Is there Fluorescence in lab-diamonds?

Yes lab grown diamonds do have fluorescence present in them. HTHP diamonds tend to have a greenish to yellowish tone to them -Although a bluish tone has been noted in some of them. The distribution of the fluorescence has a cross or hour-glass pattern.
CVD diamonds tend to have orange, yellowish or greenish fluorescence. The distribution of fluorescence in CVD’s has straight lines that seem to run parallel with each other.
Both CVD’s and HTHP’s glow longer (stronger phosphorescence) after the UV light is switched off. Some have glowed for several minutes to several days after the UV light was removed.

How are lab-gowns detected?

The appearance of synthetic gems on the market created major concerns in the diamond trading business, as a result of which special spectroscopic devices and techniques have been developed to distinguish synthetic and natural diamonds. Fluorescence and phosphorescence tests have helped to identify lab-grown diamonds

Are lab-grown diamonds cheaper than natural diamonds? 

Lab-grown diamonds are slightly cheaper than natural diamonds however the production costs for growing, polishing and marketing them is similar to that of natural diamonds.

In conclusion 

Should I buy a lab-grown diamond? 

As you can see there is very little between a lab-grown diamond and a natural diamond. Some marketers have argued that lab-grown diamonds are less harmful to the environment than mining natural diamonds. There seems to be little research that backs the statement as harmful chemicals is still used when growing diamonds. Is harmful chemicals it worse than having a massive hole in the ground? Well the verdict is pending.
It seems to come down to what the consumer decides whats best for them personally.


Sunday, 6 November 2016

Understanding the importance of a diamonds transparency



Understanding diamond transparency?


What is the transparency of a diamond?

Transparency of a diamond is the degree to which the diamond transmits light.
There are 5 categories for transparency of a diamond;

1 Transparent
Clear diamond free from any major haziness - having an excellent property of transmitting rays of light through its substance so that bodies situated beyond or behind can be distinctly seen.

2 Semi-transparent
Having very good properties of transmitting rays of light through its substance.  Very slight haze or cloudiness.

3 Translucent
Hazy and hard to see through parts of the diamond.

4 Translucent
Allowing light but difficult to see through large parts of the diamond.  

5 Opaque
Not able to see through diamond - poor overall appearance.

diamond transparency, a opaque diamond, semi-opaque diamond, diamond lights
Opaque diamond

Why is the transparency of a diamond important?

Diamond laboratories do not factor in transparency on their diamond reports therefore one can have a very good cut and clarity grade that fails the transparency test.  Poor transparency can leave you with a diamond that is hard to sell. 

What factors affect a diamond transparency?

There are many factors that impact a diamonds transparency for example clouds, structural damage, graining lines and fluorescence. Although these factors can affect a diamond transparency in a negative way it may not always be the case. Diamonds with these issues can still fall into any of the 5 categories e.g. transparent, semi-transparent, translucent etc.
The best transparency test would be to apply the rule “Beauty is in the eye of the beholder” If you a diamond and jewelry dealer you should be relatively familiar with your niche market and decide if a diamond is saleable in your market.

Does fluorescence impact a diamond transparency negatively?

Strong fluorescence can at times give a diamond a milky or hazy appearance but it does not necessarily impact the diamonds transparency negatively – again the best option would be to personally look at the diamond and decide if it is saleable in your market.