Sunday, 25 September 2016

What are Melee diamonds? | Understanding Melee diamonds

What are Melee diamonds?

Melee diamonds is a term used for small diamonds usually diamonds that fall under the 0.18 carat range.
However since shipping, grading and diamond cutting costs escalated its not uncommon to find the range of Melee diamonds weighing up to 0.30.

How are Round Melee diamonds sorted?

Sorting and grading of melee diamonds can be a tedious process. Melee is sorted by category in;
  • Round Brilliants
  • Round 8 sided
  • Fancy Shapes
  • Color (White and Yellow)
  • Clarity (IF, VVS, VS, SI, and I’s)
  • Matching pairs
  • Sizes

Round Melee is sorted though the use of a diamond sieve. The diamond sieve has different size holes in them to allow the lager diamonds to be sorted from the smaller diamonds. 
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Diamond sieve

Once these melee diamonds are sieved and sorted in similar sizes, they need to be graded. Melee diamonds need to be sorted, graded, matched and paired together in groups. Melee can also be sorted using a digital caliper. The digital caliper is useful for both Fancy Shape and Round Melee.

Melee diamonds, small diamonds, diamond chips, diamond cutting diamond polishing
Digital caliper

Round Melee Diamonds approximate mm to weight

1.        0.001 carat – 0.78 mm – 0.99 mm
2.        0.005 carat – 1.00 mm – 1.15 mm
3.        0.0075 carat = 1.16 mm – 1.23 mm
4.        0.01 carat = 1.24 mm – 1.40 mm
5.        0.02 carat = 1.56 mm – 1.80 mm
6.        0.025 carat = 1.81 mm – 1.88 mm
7.        0.03 carat = 1.89 mm – 2.10 mm
8.        0.04 carat = 2.10 mm – 2.33 mm
9.        0.05 carat = 2.24 mm – 2.43 mm
10.      0.06 carat = 2.44 mm – 2.50 mm
11.      0.07 carat = 2.51 mm – 2.73 mm
12.      0.08 carat = 2.74 mm – 2.80 mm
13.      0.10 carat = 2.81 mm – 3.10 mm
14.      0.12 carat = 3.11 mm – 3.23 mm
15.      0.15 carat = 3.23 mm – 3.54 mm
16.      0.18 carat = 3.55 mm – 3.83 mm

How are Melee diamonds graded?

Melee diamonds are graded in-house and not graded in a laboratory like larger diamonds as the costs are simply to high. Unlike larger diamonds Melee diamonds are graded in larger categories for color and clarity for example; White and Yellow and in clarity for example SI - Its not usually graded separately SI1, SI2 etc. However this can vary from company to company.

What are Melee diamonds used for?

It may seem like a waste of time to sieve and grade though large number of small diamonds. Individually they don't cost much but in larger quantities their overall value begins to add up considerably. Custom made jewelry often requires larger amounts of Melee. You will hardly find a wedding set that does not have some Melee on the sides to complement or complete a stunning setting. Melee is usually sold by carat weight and this is where the sorting and sieving pays of as a carat of Melee can start around $100 per carat to $3000+ per carat depending on the sizes, cut (Fancy or Round) and colors (White, Yellow or fancy colors).

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Saturday, 17 September 2016

How to judge the depth of a diamonds inclusion? | Diamond Inclusions

How to judge the depth of a diamond inclusions 

I remember when I was a young boy and I was sitting on the edge of a swimming pool. I noticed a leave in the swimming pool and wanted to reach out to take it out of the swimming pool. I reached further and further until I fell in. Luckily I could swim .. while I was under the water I remember opening my eyes and seeing the leave floating about halfway in the pool. I remember thinking ...well that's deeper than I imagined!

I learned a great lesson that day and that is "Never to judge the depth of anything in the swimming pool from the top" In a sense this is very true for impurities in a diamond. They can be difficult to judge by viewing it from the table (top) of a diamond.You probably wondering why its important to know where a impurity is in a diamond?

Why is it important to know how deep a inclusion/s is in a diamond?

The answer is simple - Removing a inclusion /s (when possible) could mean the difference between a SI 1 and a VS or even better. This could potentially mean a few extra Dollars or even a few extra thousand Dollars in your pocket. Now, its not always viable to remove a inclusion because the weight loss may not justify the purity gain.
Remember the Golden Rule in diamond Cutting? "You can always take weight away - you can never add weight back!"

Careful calculations must therefore be made to ensure optimum overall value. Ask yourself a few important questions.
  • What price breaks am I working with?
  • Will a VS1 - 0.90 be worth more or less than a SI1 - 1 Carat?
  •  Larger Rap price ranges (1.00 - 1.50) will give me more room but will it justify the weight loss-purity gain?

How to judge the depth of a inclusion 

The fist step is to find the inclusion and then turn the diamond around and look through the bottom. (remember the swimming pool scenario?)You will notice two inclusions. The first inclusion closest to  the culet (point) is the actual inclusions depth. The inclusion closest to the table is the actual inclusions reflection off the table. Doesn't look so close now does it?
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Judging a diamond inclusion depth

Important Note;
Note that the inclusion looks similar in characteristics - don't look at the wrong inclusion and make a judgement based on the wrong inclusions. 
We can clearly see that the inclusion in the above example is pretty deep and not worth considering removing it. In the next example we can see a inclusion closer to the table and it may be worth pursuing, provided there are no other inclusions present. There is no point in losing weight without gaining purity. We can see that this inclusion is much closer to the table.
removing diamond inclusions, diamond impurities, diamond cutting, diamond flaws
Inclusions depth

Top view of diamond inclusions.

After you have viewed the diamond through the bottom (Pavilions) you can flip it back to the table and see if the inclusion in open. A open inclusion will look similar to a little pothole in a road. Allow the table to reflect light back at you and then look for any openings. This is usually a indication that the inclusion is close to the table. However have another look though the bottom and make sure that the inclusion (even when open) does not run to deeply into the diamond.
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Viewing a diamonds inclusion from the table

However have another look though the bottom and make sure that the inclusion (even when open) does not run to deeply into the diamond. This is often referred to a the "Inclusions Tail". A Inclusions Tail can often run pretty deep into a diamond and therefore a careful analysis should be made of the length of the tail and how deep it runs into the diamond.


What other factors should I consider in removing inclusions in a diamond?

What does "Potential" mean on a diamonds certificate?

Sometimes Laboratories would send back a diamond with a note "Potential" on it. The word potential is used for The cut, clarity and symmetry. In other words the diamond has the "Potential" to be improved. For example from a Very Good Cut to a Excellent Cut . This is done where the lab has found a small problem that can easily be fixed. The word potential can be used to indicate improvement/s for clarity as well. A clarity improvement can be as simple as a deep natural left by diamond cutters but in general clarity is a large term that can refer to
  • Bearding - rough girdle
  • Bruised facets - wear and tear on the diamond, small chip marks on the facets or their edges.
  • Holes  / Cavities 
  • Chips
  • Featehers
  • Clouds 
  • Natural /s 
  • Laser drilling 
  • Fills - silicone filling in the diamonds cavities or feathers
Some are easy to improve while others are impossible to improve.
All in all you should always carefully take note of the word "Potential"as this can increase the value of your diamond (sometimes significantly).

Calculate the cost of removing diamond inclusions.

Remember to carefully calculate the cost of the diamond before and after the impurity is removed. Don't forget to include your shipping and cutting costs in these calculations.

Removing the inclusion of a diamond.

There are several factors to remember before you pursue removing a impurity.
  • You cant just work on one facet - One facet can effect several other facets and will add to weight loss.
  • The table of a diamond is the largest facet on a diamond and will quickly drop the weight of a diamond. If a table is dropped significantly you will need to re-polish the whole crown of the diamond or even the whole diamond.
  • You will lose depth and possibly diameter as well. 
removing diamond inclusions, diamond cutting, diamond polishing tips
Losing depth and diameter on a diamond
Dropping a table to remove a impurity may sound like a very simple procedure but its far from reality. Once you drop a diamonds table you could end up losing diameter and depth causing severe weight loss and therefore its highly recommenced to only seek professional advice from a proper diamond cutter - In other words - "Don't try this at home!"

I hope this blog has helped you in some mall way. I will love to hear from you and I would appreciate your expertise and input regarding this subject. I will include links to your blogs or websites if you have any valuable information for us to add to a further reading headline.
Conrad Kruger
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Monday, 5 September 2016

What are Trigons on a diamond?

Diamond Trigons 

What are Trigons on a diamond?

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Trigons on a diamond

Trigons are triangular growth marks on a diamond and they only appear on the natural pavilion faces or the 3 point face. The number of Trigons range from 1 to many and they always equilateral triangles. Trigons always face the same direction and their points always point to a natural corner or grain lines. The base of the Trigon on a natural Octahedron will always point towards the point of the Octahedron.  Trigons are helpful to the diamond cutter, diamond sawer and the diamond planner as they serve as guidelines for natural pavilions, point to natural corners and aid in finding sawing planes for diamond markers. The point of the Trigon can  be used to find the sawing plane as they always point to a sawing plane. When Trigons appear base to base it means that the diamond is twinned (where two diamonds have grown together )

Twinned diamonds often have Trigons at facing each other base to base and may or may not have a natural line dividing them. This line on the macle is a natural cleaving plane and can often cause the diamond to chip or break on this line (plane).  

I hope this blog has helped you in a small way - I would love to hear from you and will include links to your blog or website in a Futher reading heading if you have any valuable information to share regarding this subject. 
Conrad Kruger