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The largest diamond in North America.

Written by Erick Razo On January 9, 2019.

In case you have not watched the news in the last few weeks, there has been a historical happening in the geological and gemological worlds. Dominion Diamond Mines, has announced the recovery of the largest gem-quality diamond on record in North America. It weighs 552.74 carats and is of yellow color. The diamond was discovered in the Diavik mine in Canada’s Northwest Territories in October.

Diavik is approximately 135 miles south of the Arctic Circle, making it one of the most difficult mines to work on during the winter season. The average amount of snow during the winter season is 47.31 inches in Canada’s Northwest Territories. Making the terrain difficult to navigate and very hazardous.

This mine also yielded the previous record holding stone for largest discovered on the continent, the 187.7 carat Foxfire diamond, discovered in 2015. Polished, the Foxfire yielded a 37.87 carat and 36.80 carat brilliant-cut pear shape diamond that went for $1.3 million at auction.

The CanadaMark yellow measures 33.74 millimeters by 54.56 millimeters. Marked heavily with abrasions, Dominion said that it won’t sell the stone in its rough form but will partner with a master cutter to cut and polish it.  The color and texture of the diamond are a unique example of the journey that natural diamonds take from their formation until they are found. The Diavik mine has produced some of the most beautiful diamonds in the world, and this one certainly tops the list.

Man or God,.. well both…

Written by Sterling VanDerwerker">Sterling VanDerwerker On September 12, 2018.

This year the jewelry industry is rocked with the advent of “man-made” (actually man-rearranged) Diamonds.  What should I think about this?

the jewelry industry this year was rocked by the advent of affordable diamonds.  Well what does that mean,..? Carbon crystallized  into the cubic system then faceted to break light up into a pleasant mix of white and prismatic (spectral colors…) light. Commonly known to fine jewelers as simply a DIAMOND. So, does it make a difference in the beauty of a diamond. Well,.. its just another subjective choice that the consumer makes. You see, a diamond is a diamond, it just depends upon how it is, or was, crystallized. Did God make in in history or some geek with lots of high pressure really expensive equipment?  A diamond is a diamond. The most important thing is for the consumer to know what they are purchasing.  It takes a professional jeweler to inform the customer as to the nature, value and beauty of the diamond. You see,.. the internet can only go so far: it cant determine the customer’s needs and then apply product to satisfy the customer’s needs. It takes a professional jeweler to do so.

Determining needs is the skill of a real professional. Not self or profit interested, a real Jeweler can not only determine needs, but can TRUTHFULLY apply the product that meets the customer needs. 

We are in the process of manufacturing several sets of two IDENTICAL contoured wedding bands to demonstrate the same technical characteristics of round brilliant ideal cut diamonds…. one crystallized by man and the other by GOD.   

In todays’s market the consumer chooses their value unless they are willingly uninformed. Yes,.. the consumer needs a PRO. An educated and customer focused jeweler can really make a difference. Why? They can use customer focused skills to determine needs and THEN APPLY THE MERCHANDISE THAT MEETS THE CUSTOMER’S NEEDS!


Gemstone cutting : Facet machine components

Written by Erick Razo On April 2, 2018.

Now that we have learned how to pick out a rough diamond and what makes a standard round brilliant shape, the fun begins! In this blog we will begin to explain the process on how to polish and give shape to a rough stone. However, none of this can happen without the proper tools. Before we begin doing that, it is highly recommended to take facetting classes. Equipment can be expensive and it is a good idea to find some of this classes to help you try different materials and techniques used to facet a gemstone. This blog post is to help us understand the equipment used to perform the gem faceting.

 

Facet Machine-A device that allows the user to place and polish facets onto a mineral specimen. There are two major components of a faceting machine: The mast/head assembly, and the grinding wheel, or lap. A rough piece of mineral is attached to the head, and through angle, rotation, and height adjustments of the head, the mineral is lowered into contact with the grinding wheel until a facet has been ground. The mast assembly is the heart of the faceting machine. The rest of the machine is simple in construction, including the arbor for the grinding wheel, the motor that runs the arbor, a drip tank, and the controlling switches. These are described below:

machine

Arbor: Similar to the prong in the middle of a record player that you put a vinyl on, the lap (or grinding wheel) is placed onto it, and the arbor is machined to run perfectly flat when turning.

 arbor

Arbor Nut: The screw that fits through the top of the lap and secures it to the arbor.

 arbor nut

Motor: Typically the motor is housed beneath the machine and is attached by one of several means to the arbor. Motors are always velocity-variable and some can be reversed, i.e. they can turn clockwise as well as counterclockwise.

 engine

Drip Tank: The drip tank serves two purposes. 1) The friction produced from contact between the rough and the lap creates heat, which can damage the lap and create stress fractures in the stone. The drip tank allows the user to choose a drip rate via spigot and position the spigot over the lap, nearer or farther from the arbor. 2) The dust produced from grinding minerals can cause pulmonary disease if inhaled. The flow of water from the trip tank captures the particles in a slurry, which drains into a rubber container around and below the lap. This container has an exit tube that drains into a second receptacle.

DripTank

Controls: The controls are generally simple and control the rotational velocity of the lap—the key control—and sometimes the direction of spin.

controls

As stated above, the mast assembly is what makes a faceting machine a faceting machine. Its components are as follows:

Mast: A vertical pole mounted into the base of the machine on which the assembly is positioned. The pole must be machined with extreme care to ensure its perpendicularity to the lap. This is so that, when the angles for facets are chosen, they are placed at the correct angle. Facets at incorrect angles can mean a gemstone that is lifeless or transparent rather than sparkly.

mast

Dop: The piece of rough gemstone is glued or attached with hot wax to the end of a brass or steel rod, known as a “dop” or “dop stick.” The other end of the dop is placed into the quill of the faceting head. The exposed piece of rough usually becomes the bottom of the stone, known as the pavilion. Once the pavilion is faceted and polished, a jig is used to attach the pavilion to another dop, and the rough side of the stone is freed from its dop. This rough side will now become the top of the stone, or the crown.

 dop

Quill: The dop is inserted into the quill, which is lowered toward the lap to place a facet. The quill is the part of the machine that is held in the hand during faceting. The other end of the quill is attached to the main head of the assembly.

 quill

Index Wheel: If you view a gemstone from the top, you will see it has some type of symmetry. Most most round brilliant stones will have eightfold symmetry; emerald cuts have two or fourfold. In order to cut facets around a stone, the quill must be rotated around its long axis. The index wheel is what allows this to be done in a repeatable, accurate manner. For example, the index wheel may have 64 teeth. If a round stone with eightfold symmetry is being cut, the index will be set at 0, 8, 16, 24, 32, 40, 48 and 56 for each of the main facets around the stone. If a square stone is being cut, only 0, 16, 32 and 48 would be used.

 IndexWheel

Angle Adjustment: Faceting machines differ greatly in the mechanism for setting the angle of the facet. Essentially, the angle is set and the quill will then lower to exactly that angle before physically being stopped or otherwise indicating arrival at the desired angle.

 AngleSet

Height Adjustment: The depth of a facet is determined by how high or low the head assembly is, relative to the lap. The way this is determined is by choosing an angle, lowering the quill (with dop inserted) to that angle, and then observing whether and how deeply the piece of rough is contacting the lap. Generally the first adjustment will set the rough just touching the lap, so that a very shallow facet will be placed. The head can then be lowered by a micro-adjustment and the facet can be cut and re-cut until it is of a desired depth. Many machines allow the head to be untightened from the mast and slid up and down for gross adjustments, and then have a separate mechanism for making fine adjustments up and down.

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 finalized set up

 

In the next installment of this blog series, we will begin to explain and look at the cutting process.

 

Gemstone Cutting : Terminology

Written by Erick Razo On February 28, 2018.

Which shape is the best? The age old debate in the jewelry industry continues every year as shapes go in and out of style. However, there is one shape that continues to be the most highly sought after and timeless shape of all…the round brilliant cut!

Now, you may be asking “What is involved in a standard brilliant cut?” In this blog we will talk about the history and terminology of the standard round brilliant and how each part is cut to precise measurements that allows the gemstone to perform at its maximum capabilities.

The first faceted stones appeared in the late 14th century. Many lapidaries passed down the knowledge of gem faceting as family secrets. During the 19th century, the art of faceting gemstones became available to amateurs and hobbyists. Fast forward to today and you can find all kinds of literature and videos on how to perform this art. The standard round brilliant begins with the craftsman rounding out the rough stone, then a combination of facets in geometrical patterns are cut around the stone. This maximizes the optical properties of the gem and will generate brilliance that is pleasing to any beholder. There is a total of 57 facets in a standard brilliant, however, this can vary depending on the stone.

dia-anatomy

The Crown

The crown is the top section of the gemstone. It is approximately ⅓ of the height of the finished gem. A total of 33 facets make up the crown. The facets are divided into 8 main facets, 16 girdle facets, 8 star facets and 1 table facet.

s

The Pavilion

This is the bottom section of the gemstone. It is approximately ⅔ of the height of the finished gem. A total of 24 facets make up the pavilion. The facets are divided into 8 main facets, 16 girdle facets.

updated_pavilion

The Girdle

This is the section of the gemstone that connects the crown and the pavilion. The maximum height of a girdle in a standard brilliant, must not exceed 5% of the finished gem’s height.

printimages

The Culet

This is the very bottom point of a gemstone. It can be cut as a small, flat facet to prevent the gem from fracturing. This is a common practice to help the durability of stone.

Culet

There you have it; this is the parts of a standard round brilliant. Not all gemstones are cut into this shape, many times the shape is dependant on what type of stone is being cut, and how included the rough is. The decision of what shape to cut the stone into is essential as it will affect all the steps that we will learn about in the next blog post.

 

Gemstone Cutting : Picking Rough

Written by Erick Razo On February 10, 2018.

Gemstones have been part of history since ancient times; their beauty has captivated kings, pharaohs, emperors and everything in between. Fast forward to today and the beauty of gemstones, continue to fascinate us but how does a gem become so beautiful? There are many steps necessary to facet a stone from its rough form to its beautiful finalized form. This series of blog posts are focusing on each step of the faceting process. Today we begin with the first step in the process.

Step One: Selecting the rough.

Rough is the term used to describe the gemstone that has not yet been polished or cut. All gems have unique crystal structures that determine the way they grow and can affect the shape that they will be polished into. When choosing rough, these three factors are essential: clarity, color, and cleavage.

SapphireColored_404

Sapphire rough, pictures courtesy of GIA.

aqua

Aquamarine rough, pictures courtesy of GIA.

topaz

Topaz rough, pictures courtesy of GIA.

The clarity or the clearness of the stone is determined by the amount of inclusions, cracks or other minerals within the stone. To be able to decide on the clarity, gem cutters utilize oils or liquids that can help them see inside the crystal from the outside, just like a window. Under at least ten power magnification, gem cutters then look for any factors that might affect the clarity or become a potential threat to the structure of the finalized piece.

looking though

The goal is to find a stone that does not contain a lot of inclusions. Which is easier said than done. The art of faceting a stone allows for the cutter to find and analyze the best way to deal with any inclusions in the stone. Once the clarity is analyzed, the orientation of cutting gets mapped out for the maximum recovery of stone weight. A wrong decision in the cutting orientation can be costly and could even cause a complete discard of the rough.

The next step is color, which is the most critical value factor of this entire process of choosing a rough crystal.The term color zoning refers to the uneven distribution of color within a gemstone. Which leads to a question is the color uniform through the entire rough? Is it lighter one side more than the other? Many stones contain more than one band of color, is essential to orient the banded rough so that the pavilion (bottom part of a faceted gemstone) is entirely within the banding when is cut. The pavilion must not protrude past the color zone point, to avoid a loss of the desired color.

color zoning

Obvious color zone in Emerald Even color in Emerald

Cleavage – The tendency of a mineral to break along flat planar surfaces as determined by the structure of its crystal lattice. These two-dimensional surfaces are known as cleavage planes and are caused by the alignment of weaker bonds between atoms in the crystal lattice. The cleavage planes will help orient the stone to the angles needed to prevent the stone from chipping.

5-1-topaz-orientation-standard-brilliant-cut

Now we know the basics of picking rough, is a skill that takes time to develop. Remember that practice makes perfect! In our next post, we will begin to identify the parts needed to polish the rough into a beautifully polished gem.

 


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