Fluorite - an optical and practical challenge

Below are high resolution animated renditions of Fluorite designs shown in an article to be published in the UK Facet Cutters' Guild's magazine, Faceters' Stonechat. The same hue, saturation and transparency have been used for all. In the near future these images will be replaced by those reflecting the remarkable properties of gem quality Fluorite currently being produced by UK Mining Ventures (http://www.ukminingventures.com) from their Rogerley and Diana Maria mines at Frosterley, Weardale, County Durham.

CaF2R by Steve Sweetman October 2020

Apex Square Fluorite by Tim Smith January 2006

FLUR17G.GEM by Jim Finlayson November 2013

Marvel Star (apex) by Steve Sweetman August 2015

Marvel Star (apex mirror) by Steve Sweetman October 2020

Chequerpoint Charlie by Steve Sweetman October

2020

BEST SCORE YET!

UK Facet Cutters' Guild

2020 Open Competition

Lockdown had one positive outcome. Unlike 2018 when I had to rush my Open Competition entry and 2019 when I was unable to enter for a number of reasons, 2020 gave me an opportunity to spend some time on my stone and had it not been for one very small error when polishing a crown facet I might have done better than I did (99.39%). This had to be corrected by revisiting adjacent facets (I thought I had got away with it!) and it is testament to the skill of the judge (see comments below) that he spotted this and a number of other very minor defects that I was unable to detect.

There were eight entries this year and the results were as follows:

Tim Smith 98.81% but x 1.02 for degree of difficulty as his submission was cut in fluorite. Total 100.79%. Congratulations to Tim on coming a worthy first.

Steve Sweetman 99.39%

Jim Clark 99.19%

Aleksander Zunic 99.01%

Ivan Williamson 95.76%

Mark Nuell 95.22%

Jim Finlayson 90.91%

Mike Hitchman 84.54%

Here is the deceptively simple looking competition design and a photo of my entry.

Here is my score sheet and and the Judge's comments.

I like the comment concerning "a world class level of skill" but must do better!!

Gem Cut Studio Version 1.1

The new and improved version of this versatile and dynamic gemstone design and optimisation software is now available for download here: - https://gemcutstudio.com/download

Available free to existing users and as a 30 day free trial. No vested interest but I recommend this. For GemCad users it takes some getting used to but, based on personal experience, is easier to get to grips with.

Here is the design shown above as resequenced, annotated and 'cut' in GCS and the resulting facet diagram.