8-fold symmetry - just some theory

[Garry H (Cut Nut)]

Date: 2/14/2008 10:02:46 AM
Author: adamasgem

Date: 2/14/2008 12:52:22 AM
Author: Garry H (Cut Nut)

Date: 2/14/2008 12:28:31 AM
Author: adamasgem

Date: 2/13/2008 11:05:18 PM
Author: Garry H (Cut Nut)

Wink it is impossible to see any other colour than a spectral color. There is no mixing of wavelengths unless the gemstone is doubly refractive like this faceted calcite from the Smithsonian. (Diamond is singly refractive)

Garry.. You might rethink your comment. Is white a spectral color?

Hi mate, no need to rethink Marty
http://www.gemology.ru/cut/english/grading1/4.htm

Garry.. Cut effects the ability to resolve spectral colors

Marty there is no arguement about that.
But fire is a difficult thing to quantify.
We have intensity of fire, range of colours seen at any time, all sorts of stuff.
Not easy to resolve. i think Sergey has played with around 15-20 metrics and is still not 100% happy.

 

[Serg]

Date: 2/11/2008 10:39:37 AM
Author: Paul-Antwerp
There are very important points that you are all forgetting. Consumer-power and interpreting their desires are strategies with serious limitations.

To start, the rough that cutters are buying, is very expensive. Like Diagem puts it, it reduces the cutter''s propensity to experiment.

One of the reasons why rough diamonds are expensive, is because too many consumers are indeed, Garry, still buying diamonds as a commodity, without any regard on quality whichever way you want to express quality. It is because of this basic demand for ''whatever'' diamond, that huge cutting houses can afford to cut ''whatever'', and use their economies of scale to generate profits. We have a huge task ahead of us of marketing ''quality'' in diamonds, not only to the PS-public, of which more than half is already converted to quality, but to the public in general. In order to achieve this, quality-people should work together, and stay away from the bickering about ''my quality-product'' is slightly better than your ''quality-product''.

At this point in time, almost no consumer is willing to pay considerably more for a quality-diamond. Even while we are talking that certain ''quality-products'' command a premium, in fact, coming from the same rough, most cutters are very happy if they bring in the same money as a general low-quality diamond. It is because consumers do not grasp that weight, colour and clarity are not actual describers of a diamond, they perceive cut-quality as an indicator of a higher price, while this is often not true.

As for consumer-input, Storm, I really respect your efforts in Diamcalc-designing, but when this has no relation with actual rough, it is meaningless. To start, one cannot design without considering the weight-loss.

Second, in DC, one is always designing absolute symmetry. Now, I fully agree that this contributes to overall performance, but the more sophisticated the design, and the more into small details a design is, the more limitations in cutting-technology make it difficult to impossible to achieve this design.

Finally, looking at these specific DC-designs, they look great at first sight, on a stone with a diameter of 60 mm. But we should reduce each design to its real size, and then, I fear that too many small virtual facets will take away from the performance of these designs. In a sense, a majority of diamond-cutters make this same mistake, based upon tradition, by creating faceting-patterns with more facets, thinking (even claiming) that this results in better light-performance. In reality, unless it is a really, really BIG rock, the only result is too many and too small virtual facets, where fire becomes difficult to observe, and where one has no big-size scintillation.

Live long,

Paul,
re:I fear that too many small virtual facets will take away from the performance of these designs. In a sense, a majority of diamond-cutters make this same mistake, based upon tradition, by creating faceting-patterns with more facets, thinking (even claiming) that this results in better light-performance. In reality, unless it is a really, really BIG rock, the only result is too many and too small virtual facets, where fire becomes difficult to observe, and where one has no big-size scintillation.
What is about princess cut which has much more number virtual facets than Asscher cut?
Is princess cut bad for your opinion?

re:To start, one cannot design without considering the weight-loss.

More news cut give more opportunity for better yield. You can design new cut for special rough shape or opposite way, firstly design new cut then find profitable rough shape.
Be free in you choice

re:but the more sophisticated the design, and the more into small details a design is, the more limitations in cutting-technology make it difficult to impossible to achieve this design

may be better way to improve cutting-technology?