Australian Facetors' Guild Limited

Ask all your question here for the 2024 competition.

Hi Gordon, what has changed in Release 2?

Hi Paul,

The committee wholeheartedly apologises to Andrew for the mistake.   We didn't see the woods for all the trees. 

When the design was entered into Gem Cut Studio to allow all diagrams in the competition Schedule to be presented in the same format, the C1 angle wasn't added, meaning that the last angle used (P3) was used instead of the C1 angle.  This meant that the C1 facets didn't meet the table and the shape of the C2 and C3 facets was changed.

Luckily Rick agreed we could update the diagram, but entries cut to either diagram will be  accepted to be fair to entrants having already cut an entry using the incorrect diagram.  The statistics for both stones are in substance the same as the table height and dimensions are governed by the C2,C3,Table meetpoint.

The other, but not as nice solution would have been to re-label the incorrect diagram something like "Committee's Mistake" or "Ah Whoops", which in my view isn't as appealing as Andrew's design, although the optical performance is very similar due to Andrew's pavilion design and the height of the Crown.

Entrants who have not finished cutting their entry for section I.10.3 now have the choice of finishing the stone as is or lowering the C1 angles to the correct  angle so the C1 facets meet both at the C1,girdle meet and the C2,C3,Table meet.

Regards

Gordon Perkins for the 2024 Competition Committee

Hi All,

We have had a query about the diagram for the Pear No. 3 by Evan Williams, Section O.10.3.  The diagram in the Competition Schedule has a Pre-form and the original diagram on page 140 of Australian Facet Designs by Evan Williams, compiled by Hank Prins didn't.  Hans E. prepared the preform to make it easier to cut.  I was proof cutting to the original design and spent a lot of time on getting the girdle outline right due to the relatively shallow angle changes in the Pavilion.  Hans' pre-form made this easier and he completed proof cutting the stone before I finished the pavilion.

I confess I made a change to the C15 facet angle when preparing the diagrams for the competition.  The C3,C4,C13,C15 meet point does not quite meet in the original design and I felt as a committee we should at least have all meets in the diagram meeting up.

So the bottom line is whether you use the diagram in the book or the Show Schedule you will get the same stone, the judges won't know how you got there and it doesn't matter.  The same goes for re-organising the order in which you cut the facets (although you'll have a hard time re-organising how you cut rows P8 to P:23 of this design if you have not used a pre-form).

One further point.  Evan's original design was for Sapphire and we are using Topaz.  As the RI lowers you need to start making hard choices as to whether you optimise the stone for maximum table reflection or maximum all crown facet reflections.

Optimisation

It's the cutter's decision as to whether or not to adjust the height of the crown or pavailion or both using the tangent ratio method to adjust the performance of the stone.  Both GCS and Gemcad do this automatically. 

This is permitted by the rules as this does not change the shape of the facets when the stone is viewed by looking along the C Axis (top and bottom views).   

Of course the facet is elongated or shortened when viewed from the side otherwise the stone would not work. 

This is different to simply changing some of the facet angles, or even all of them by a set amount.  That method may work for a round stone, but it changes the facet shape and the judges will pick this up.  I doubt it would work at all on this design.

One last point on optimisation, this affects the Visual effect score (6% of the overall mark).  We have set out to provide designs which perform well.  But in some designs there are trade-offs and everybody's view of how a stone should be optimised is personal.  In this design, how the stone is set (i.e. in a ring or as a drop) can influence those choices. 

By the time a cutter is competing in the Open competition one view is that the competitor ought to be able to critically appraise a design and have the latitude to adjust its performance using the tangent ratio method.

Happy Faceting.

Ugh!  Sorry everyone, I was thinking of the approximate date by which you would need to post your entries within Australia for them to be received by the 1st.

The actual date will depend on where you live and whether you use express or ordinary post.

Don’t forget your competition entries need to be in the Committee’s post box on or before the deadline specified in the competition schedule.

Happy faceting