Diamond Cutting Polishing a beginners guide

There is only one quality of a diamond which we control, diamond cut.  Don’t confuse diamond cut with diamond shape, for example a round brilliant cut diamond. . The cut refers to how well the stone is cut, the qualities of the diamond – how well the cut unlocks the diamond’s fire and brilliance.  It all comes down to the skill of the diamond cutter.

rough diamonds before they are polished octahedron shaped

The process of transforming rough diamonds into polished diamonds is amazing.  Taking a “rock” and making it into a thing of beauty involves tremendous experience and precision.  The process takes place in several stages: planning, cleaving or sawing, bruting, polishing and final inspection.  At each stage a diamond cutter or jeweler uses specific tools to bring out the unique diamond waiting within.  Let’s go through the process.

Planning: Analyzing the diamond to determine how it will be cut.  Computer-generated 3D images of the uncut diamond are generally used in the evaluating process.  Using these 3D models diamond manufacturers are able to assess the best angle for getting the best color, as well as for cutting and faceting the diamond.  The diamond facets are the windows of your diamond.  If cut properly, the light that enters will reflect back to your eye resulting in superb brilliance.  As you can understand, some raw diamonds are better suited for a round brilliant cut diamond while others would best be used for a longer diamond shape, like an oval shaped diamond, a pear shaped diamond or a marquise shaped diamond.  Even before the cutting process begins this is a crucial decision to be made.  For the manufacturer, it’s a question of getting the most out of a stone and being able therefore to get the most money.  For a consumer, it’s a question of whether the diamond is cut with the correct proportions to allow for maximum brilliance.


sawing a piece of rough diamond this is usually the first cut

Cleaving/sawing: Some raw diamonds are used for a single stone while others are made into several separate diamonds.  This decision is made in the planning stage and will be finalized in the bruting stage.  For now we are concerned about the rough cutting down of the stone.  Cutting tools such as blades, saws and lasers are used in separating a rough diamond into smaller pieces.  The blades and saws generally utilize diamond dust or industrial diamonds in order to cut the diamond to the desired shape.



diamond bruiting making the diamond the shape it will end up Bruting:
This term is also known as girdling and is an important part of the process.  Here the rough diamond begins to take real shape.

It is rounded into a conical shape which will then be worked on further.  The main tools used in bruting are the lathe that rotates one diamond and a dop that rotates another diamond.  Some diamond cutters use digital imaging in the bruting process to analyse the desired dimensions and determine the speed of rotation.  At this stage a diamond loupe is often used to determine how best to show off the stone’s best attributes as we prepare for polishing.



diamond polishing of the facets on the diamond polishing wheelPolishing: Both cutting the facets of the diamond and the final polishing are included in the polishing process.  For the faceting process, a diamond cutter creates each facet using a dop to hold the diamond at the correct angle, grinding the diamond against a blade while spinning it with diamond powder and a lubrication like oil or lanolin.  This process is repeated for each facet of the diamond.  A polishing wheel and polishing pads are used to polish faceted diamonds and is a time consuming process.  This stage is for removing any coarse marks left from faceting the diamond and for ultra-fine polishing to bring out all the light-reflecting properties of the diamond.


Final Inspection: After the long polishing process each diamond is carefully evaluated.  If an external flaw is found it can be sent back for further polishing.  In some cases manufacturers choose to use enhancement techniques that fill in cracks for example.  Surya Intertrade Co., Ltd has a strict policy regarding these diamond enhancements.  Absolutely no color adjustments are made and the use of heat treatments are completely forbidden.



diamond polishing and planning of the cutAt this point, once the final inspection is complete, the polished stones are ready for diamond certification.  In terms of cut grade, a polished diamond is assessed and given a cut rating of: excellent, very good, good fair or poor.  Some stones are not certified, which we strongly advise against as there is no other way to insure that you are getting what you paid for.


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