Eye Of Comstock

I have finished a modified Cleopatra’s Eye cut (designed by Bob Keller) in Gladstone smoky quartz. I have called it the Eye Of Comstock after the historic lead-zinc-silver deposit, west of Zeehan Tasmania. The modifications to the cut I made were mostly in the crown of the stone, I left off the top couple of tiers of facets and free-wheeled the pupil in. I also nicked both ends of the stone to reduce the chance of any girdle chipping in this area if the stone is set into jewellery.

pavilion view

The stone is of a suitable size to make a nice cocktail ring or pendant: L x W x D = 25mm x 18mm x 16mm approximately, for a weight of 32.6 ct. It is a very clean stone ~ eye clean, with nice colour saturation – not too dark to affect the optical performance of the stone, but rich enough to add a nice level of complexity to the final effect. The light return in this stone is stunning.

Colour bar from Whisky Magazine

Perhaps a 1.3 – russetmuscat on the whisky chart…. Na zdraví.

side view

For Sale – enquiries via the Zeehan Rock Shop

SG Calculation

I do see a lot of people doing SG’s the hard way using all sorts of jigs and contraptions to try and measure the weight of the stone in water. There’s a simpler way – you just need to measure the weight of the water displaced by the stone when fully immersed.

You will only need an accurate carat scale (accuracy to at least .01g), a small beaker/glass of water, a calculator and some fine cotton.

Weigh the piece of aquamarine: 2.06g
Tie some cotton to the stone, use a slip-knot, or make a little cotton sling for small cut stones.
Zero a beaker of water on the scales
Measure the weight of the water displaced by totally immersing the stone supported by cotton, just below the surface, not touching anything: 0.76g

Divide 2.06 by 0.76

Answer: 2.71

That’s it; done.

Walter Schumann Gemstones of the World says for aqua SG: 2.68 – 2.74

Bang in the middle!

Tubelite

I recently went on a short prospecting trip to the south-west of Tasmania with a couple of friends. The main aim was to locate some streams that might hold a bit of alluvial gold. We ran into a lot of problems with road access – forestry roads that were closed due to the bushfires from last summer or for other reasons, so did not really achieve our aims.

On one small track that ended in a small disused quarry, a shattered old TV set lay on the ground, dumped years ago by some vandalous low-life.

Tubelite..

This was one of those old bulky TV sets with a glass CRT Cathode Ray Tube (yes, you heard right youngsters – no flat-screen in sight here). Flat screen TV’s apparently out-sold CRT TV’s from 2008 onwards to give you some point of reference. The glass TV tube was now simply a collection of angular glass fragments of different sizes and shapes scattered amongst the crushed TV shell and around in the nearby vegetation. No doubt the unknown person(s) who went to the trouble of transporting it all the way out here in the wilderness had also taken perverse pleasure in enthusiastically imploding the cathode ray tube with whatever lay at hand. So had it been a family outing? C’mon kids, stop watching that new Samsung, we’re going for a drive in the country, bring a warm jacket and your favourite rock.

On discovering the technological remains of times past, I began to think of the irony as I bent down to collect some pieces. As it happens, the glass used in the manufacture of CRT’s was very good quality glass of specific properties. I know this because I have faceted CRT glass before, and it is remarkably clear optically – high clarity with very few visible inclusions. The colour of this glass varied from shades of grey, to bluish-grey to yellowish brown, however I suspect the yellowish colour may be a weathering effect.

If we consider synthetic rough versus simulant rough for a moment:

In contrast to synthetic gemstones which have the same chemical composition, crystal system and physical constants as their natural counterparts, a simulant need only have a superficial resemblance to the gemstone it imitates.

Gemmology (Peter G. Read, 1991)

So, on this day instead of finding alluvial gold, I had found what in effect was gemstone rough – or at least a simulant “LG-ite” – the LG branding still visible on the shattered TV case.

I have also sourced CRT glass in the past from beaches near Hobart, deposited there as the result of nefarious activities – Rank Arenarite? The further irony being that CRT tubes are no longer manufactured, so this glass will become rarer and rarer as time goes on – much like natural gem material.

As an addendum, it must be cautioned that CRT glass can/does have a significant lead oxide (PbO) component. So it is probably not a good idea to work with this material for extended periods, or long term, due to the potential health risks of lead.

The Eye Of The Beholder

I got a fantastic facet-grade Gladstone smoky quartz crystal from Richard at the Zeehan Rock Shop.

Gladstone champagne-coloured smoky quartz crystal

The aim was to create something big, interesting and unique. Now, the crystal was already just that in its natural state, so I decided to try and preserve some of what made it so nice already, while at the same time exposing some of its other beautiful features. One of the neat properties of the crystal is the well-formed hexagonal cross-section, I decided to preserve this natural six-sided prism shape whilst still using faceting techniques to add something extra – in an optical sense.

Showing scale, Zeehan in background!

I wanted to ultimately cut two stones out of the crystal, so I sliced it neatly – almost in half. The crystal termination (or pointy end) made for a good natural preform for a pavilion.

I chose a hexagonal cut for the pavilion facet component, “Hard Roku” by Marco Voltolini.

Hard Roku faceting design to be used.

So, I created the pavilion according to the angles of the Hard Roku design above, with an interesting transition from polished facet to dimpled natural crystal face. The natural but imperfect hexagonal crystal shape meant that the faceting is not exactly symmetrical, but I like that – and I think it works.

Natural slightly water-worn hexagonal crystal faces still visible on the side

I called  it “The Eye Of The Beholder

That big round facet up front took hours to polish. The effect is mesmerising, like a natural kaleidoscope – at the right angle you get the ability to look far into the optical and crystallographic axis of the crystal, in fact an illusion is created where you appear to be seeing further than the length of the stone itself, into what eerily resembles an eye. Note that it is very hard to capture this effect in a photograph, however.

The rim is frosted and light from the back facets projects onto it.

The Eye Of The Beholder (side)

The stone came in at about 48 grams, and 40mm across the flats at the widest dimension.

Video above courtesy of the Zeehan Rock Shop.

Silver City Souvenirs (Zeehan Rock Shop)

I sell my stones at the fabulous Silver City Souvenirs rock, gem, jewellery and mineral shop in Zeehan, west coast of Tasmania. It can be found at 131A Main Street, Zeehan (0438 448 904).

I highly recommend visiting the Zeehan Rock Shop, the knowledgeable proprietor, Richard, will be able to answer your questions regarding minerals and rocks in the West Coast area and has many stunning items to purchase.

I have examples of my Gladstone smoky quartz faceting work in the glass cabinet at the front counter in the shop if you wish to see some stones close-up.

I travel to Zeehan regularly for work, and have been doing so, on and off, for about 10 years now. In fact my association with Zeehan goes back to 1994 and earlier. I remember visiting Zeehan when I was a child – must have been back in 1980 or thereabouts, and buying some specimens as well as having a bit of a fossick. In 1994 I worked in Zeehan for a year with a large exploration company, using a room in the Heemskirk Hotel as an exploration geology office. I worked out in the field every day, it was quite an experience.

Gladstone smoky quartz

Gladstone smoky quartz (cuts are modified Voltolini designs)

Gladstone, a small town near the Ringarooma River (in the north east of Tasmania, Australia) is located close to some old tin and gold historic mining sites. The alluvial tin miners were not at all interested in the abundant smoky quartz crystals which were commonly encountered whilst they were working the small creeks (Ah Kaw Creek, Mt Cameron Creek and Alhambra Creek in particular). These crystals and other detritus where piled up in areas out of the way (above the creeks) and now form the focus for fossickers to the area.

There are many nice, slightly water-worn crystals of smoky to be had from the area, however I find that material suitable for faceting comprises only about 2-3% of the smoky crystals typically found here. This is still good, because some quite large examples of smoky can be found, and it is not that hard to find half a bucket or so in a day’s fossicking, so a few percent of ‘quite a lot’ still makes for plenty of faceting action.

Champagne-coloured facet-grade Gladstone smoky quartz

Same again.. note the slightly rounded water-worn crystal faces.

There is also smoky quartz to be found on Mount Cameron itself (see examples from the Zeehan Rock Shop below), these often well-shaped crystals are not water-worn, with parallel striations still often visible on the crystal faces.

Mount Cameron smoky quartz for sale in the Zeehan Rock Shop

I often like to cut Gladstone smoky into both buff-tops and opposed-bar cuts. Initially I favoured opposed-bar cuts such as Jeff Graham’s Smithsonian Bar, however I have found that inverted bar cuts designed with the crown facets parallel to the long axis of the stone create a more pleasing effect to my eyes (see diagrams below). The publicly available design: “Htims Bar” by Marco Voltolini is a great example of this style of cut, and lends itself nicely to the Gladstone smokies.

Htims Bar design by Marco Voltolini

Smithsonian Bar design by Jeff Graham

Frome River sapphires

I have been provided with some sapphires from the Frome/Weld River area (NE Tasmania) to cut for an avid prospector. The two I will begin with are quite different in nature. A smaller stone with good clarity and light colour, and a larger, quite dark blue stone, with distinct growth bands visible.

Gee, Tasmanian sapphires when well-coloured can match it with the very best.

Frome River (NE Tas) sapphire, 2.2ct

5.5ct sapphire: dopped and ready

This large stone, dopped above, would benefit from being cut as shallow as possible to help lighten it, whilst still considering the critical angle of 34.45°. I think the Jeff Graham Quickie 2 may be a good choice @ 91.2% light return.

Quickie 2 cut

Ok – update, having started the pavilion, some cracks that were not visible before cutting, due to the darkness of the stone, are clearly apparent now. This is a typical example of the sorts of challenges that often present themselves during the cutting process.

This has lead to a rethink as to the best cut. The roundish Quickie would now yield unacceptably low, a more rectangular stone would be better so that I can cut the defects off without losing too much stone carat weight.

Obvious cracks and defects

This angle clearly reveals the growth lines

Changing to a rectangular cushion cut, the Tsunami-311 in fact.

Rectangular cushion cut – Tsunami 311

Looking better, still some more to cut off top-left

And better..

Good!

Time for some polishing

Pavilion polished and ready for transfer

Transfer in progress – epoxy on top, wax on bottom.

Crown underway

So far, so good

Table is in

Interesting stone – this cut is much harder than I thought it would be..

look at those bands!

Shiny as.

Pre-polish was tricky, but all done now, very pleased. Final polish next.

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NW Tasmanian (Table Cape region) sapphire and zircons

NW Tasmanian sapphire and zircons

Above are some largish well-formed examples of Tasmanian stones sent to me for cutting a while back. The 4.9 ct  sapphire pictured above is a nice example of the dogs-tooth shaped crystal habit.

I examined the sapphire above and tried to determine the best orientation, taking into account inclusions/cracks etc.

Dopped and ready

I decided that the orientation above would give the cleanest stone with the highest yield – so many factors involved in creating the best final product. A rectangular cushion cut, the Tsunami 311, as per this post was the selection.

Pavilion underway. If you look carefully you will see a small crack on the RHS near the girdle area

Crack a bit more clearly visible. It should cut out OK.

Another view, crack is original with some iron oxide present.

Fixed and continuing with pav. Yield down a little.

Prepolish going in, nice colour coming through now.

Final polish on pavilion (I know I’m really slow, lol)

final polish #60K diamond

Transfer for crown – great colour!

epoxy on top (with filler powder added to reduce runniness and increase strength)

On to the crown..

OK, just cut the two A facets on the crown

B crown facets

B crown facets

H facet in, about to do I facets

Table facet in

All facets done, time for pre-polish

Pre-polish going well, you can clearly see the unpolished frosted H and I facets adjacent to the table standing out

H and I facets left.

Pre-polish complete

Final polish ahead.

Most facets done, ready to put the final polish on the table

Table adapter on

Shiny, shiny, bad times behind me!

This is one sweet Tassie stone

Stunning.

This stone turned out real good..

Yield was a little lower than I would have hoped at the start, however this is a really clean stone as a result, great colour (and great cut too I must say!)

 

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For the love of smoky quartz

Some of my smoky quartz cut to modified Marco Voltolini designs

Natural smoky quartz is neat stuff – I like cutting it very much. It is a common gemstone, certainly in large crystals suitable as mineral specimens, and a little harder to source in facet quality natural (read non-synthetic) pieces. The other macro-crystalline (crystals recognisable with the naked eye) quartz gemstones commonly obtainable such as amethyst, citrine, rose quartz and ametrine etc. don’t really inspire me the way smokey does for various reasons.

Now, the quartzes just mentioned do all occur naturally – however a certain amount of cooking (heat-treating) is usually undertaken to obtain the desirable hues and colour effects seen in citrine and ametrine. Citrine/ametrine are found in nature, but they are quite rare, so it is safe to assume that most of the material you are offered for purchase has probably been heat treated.

This kind of treatment for quartz gemstones is generally considered acceptable in the trade, which is understandable in the current times for some important reasons. The recent emergence in the market of low cost synthetic man-made quartz (produced using the hydrothermal method mimicking nature) has meant that it has become easy to source huge chunks of near-perfect colour and clarity quartz for a pittance on sites such as Ebay etc. This synthetic quartz rough can look like the stuff that some fossicker has carefully chipped off a rock face with a geopick, or it can even display natural looking crystal faces, yet it is often marketed as natural, usually “mined in Brazil” lol . The near perfect looking stuff you can buy (cheaper per kilogram than a bunch of bananas at your local grocer ) is easy to label as synthetic. Smaller parcels of finer coloured material offered at a higher price per carat is where it starts getting very, very tricky, or in some cases virtually impossible to verify it as natural, even after formal testing by some gemmology labs.

Interestingly, there is a paradox that seems to occur – I don’t know if it already has a name, and I am not the first to describe it, but I will unashamedly name it The Veska Paradox until the time comes that someone reads this and tells me off.

The closer you get to the mine or source of a gemstone, the higher the probability you will be dishonestly offered synthetic or simulant material instead

So, you see that some natural quartz material that is truthfully declared as heat treated is not so bad in the greater scheme of things.

So, back to smoky quartz. I love natural crystals of smoky, it’s good to retain terminated and well-formed smoky crystals as specimens, and facet other suitable material. With smoky it is possible to create cut gems with fine tasteful natural colours including tones resembling an whisky aging on oak (see colour bar below)

Colour bar from Whisky Magazine

With amethyst rough I have come across, the colours can be very deep and vivid, however I personally find finished stones a bit tacky and/or overbearing in many cases. Citrine can have some nice tones overlapping the colour bar above, but I also find the colours a bit unreal in many cases.

If a jeweller wants to make a large jewellery piece such as a necklace with lots of high carat gold, and also wants to include some large cut stones in the design whilst still keeping the piece elegant, tasteful and less than the cost of a small house then what to do? To prevent the piece from resembling a shopping mall chain store trinket, an arrangement of fine coloured, well cut smokies in the design can fit the bill nicely.

OK, a quiz for you below: Synthetic or Natural?

Exhibit A: typical material I work with

Exhibit B: 99ct, Ebay starting bid USD $5

Exhibit C: 775.6ct, Ebay starting bid USD $2

Place your thoughts by using the comment box below – Answers coming soon!

 

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The cutting equipment

Facetron faceting machine

All stones at Rough Creations are cut on a Facetron machine (pictured above). This USA built machine is very user-friendly with good build quality and ease of use. It has a few irritating quirks, but once one is familiar with these, it is a pleasure to operate.

I use 8″ Gearloose polishing laps where possible – they have been very effective in practice for me, and I highly recommend them.

Pre – polishing the table facet with the Facetron and 45° adapter

It’s worth a mention regarding the gear I should have been using. What I mean by that is I should have been using a desk or bench for my faceting machine that was height adjustable or at a comfortable standing position. I am and have been incapacitated for over a week with a bad back, and I believe at least some of the blame is due to my bad posture when sitting at my machine working, sometimes for hours at a time. So fellow faceters – watch your backs!

Flat on my back with some pain relief at hand.