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Fossicking Locations / Re: Victorian Sapphires

« Last post by RoughCreations on Today at 10:51:40 AM »

Thank you. And you would expect a 1mm finished jewel if all goes well?

Hi Alaskan,
Remember that the final yield is a percentage of the original rough's weight, not width or other dimension.
For example, a 10mm diameter Standard Round Brilliant (SRB) sapphire would weigh about 3.65ct, a 9mm would be 2.66ct, an 8mm would be 1.87ct, a 7mm would be 1.25ct, and a 6mm 0.79ct and so on, according to my Gem Cut Studio size/yield calculator. So in this example, in going from 10mm to 7mm diameter, the carat weight has dropped to ~ one third. That is, the relationship between the width of a cut stone and its weight is not linear.
In other words, a spherical-shaped 3mm diameter (mythical) sapphire cutter found while fossicking would weigh about 0.3ct in its rough uncut form. If it was cut into a SRB, the best theoretical yield achievable would be a cut stone of 3mm diameter, weighing 0.1ct giving a yield of 33%.
In a more real-world scenario, where the 3mm rough sapphire cutter was a bit more irregular in shape, it would weigh a bit less than 0.3ct, and we may expect a yield closer to 25%, this would equate to perhaps a 2.7mm stone (.07ct) in our SRB example.
So, in summary, a 1mm finished jewel from a 3mm rough would be a bit disappointing! I reckon you could do better than that on a rainy day with good karma and a hot cup of cocoa, lol.

RC

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Fossicking Locations / Re: Victorian Sapphires

« Last post by Alaskan on Today at 06:51:23 AM »

Thank you. And you would expect a 1mm finished jewel if all goes well? It takes me 3 hours to cut and Polish six facets - usually a week to do a pavilion. Today I cut six tiny girdle facets - P3 on AB's Supernova - on lab created Zircon and wonder how anyone can cut two stones per day?

1500 - 8000 x 6 facets in 3 hours.

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Fossicking Locations / Re: Tomahawk creek

« Last post by MakkyBrown on May 19, 2024, 11:49:07 AM »

It is a bit of a maze, I drove all over the place and it is hard to figure it all out, need to make a map or use satnav. Yes, Feather Bed Run is in pass the caravans. I drove out to Mt Hoy, end up following a fence line, crossed creeks and having to turn back. Endup in an old hole up behind the tip till the wash pretty much ran out and it also got pretty dangerous so I collapsed it all and walked away.

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Fossicking Locations / Re: Tomahawk creek

« Last post by Scratcher on May 19, 2024, 10:42:24 AM »

Ok all, I made it out for a few days, heaps of old digging out there. Cleaned up and old digging on the ridge to the right and got some wash. Very grassy up there, moved down to hut creek and cleaned out another old digging. Got some nice wash before it ran into an old digging, ended up with a few chips and 3 nice sized ones. Went for a drive around couldn't find the feather bed is it passed the caravans or os there another road? Was going to have a look at Mt hoy but the tracks split up and go everywhere up past the lodge. Will get more adventurous next time. Do NOT ask google how to get to tomahawk creek from Clermont. Took me 60k down into a farmer's back paddock. To a locked gate   

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Fossicking Locations / Re: Victorian Sapphires

« Last post by swirly on May 19, 2024, 03:50:32 AM »

around 3mm.

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Fossicking Locations / Re: Victorian Sapphires

« Last post by Alaskan on May 18, 2024, 09:14:05 PM »

What do you consider a 'cutable' size? Been wondering at what dimension to draw the line... a dop size that won't bend? Just curious as I have little experience in selecting material.

Swirly mentioned cutting size.

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Trip Talk / Re: The Next Big Trip

« Last post by Jimnyjerry on May 18, 2024, 06:56:45 PM »

That will be a interesting trip Barry. I am just hoping to get back to Agate Ck next year as it will be 4 years since I last could visit.  Seems the grass has been really growing well this season.

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Trip Talk / Re: Flinders Island 2024

« Last post by Jimnyjerry on May 18, 2024, 06:53:36 PM »

glad you enjoyed your visit down there and good to hear of the conditions of the islands fossicking locations 

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Fossicking Locations / Re: Victorian Sapphires

« Last post by Manficat on May 18, 2024, 05:24:26 PM »

Ah, I see. I'll try Dollys creek and that other area again. I presume any section of Dolly's creek is fine, right?

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Trip Talk / Flinders Island 2024

« Last post by MakkyBrown on May 18, 2024, 12:34:23 PM »

I just spent a few weeks on Flinders Island. Lots of walking, taking photos and digging topaz. Since visiting about 10 years ago it has become really hard to find topaz around the Diamond Gully area. When digging ground I where found topaz last trip, it appears, the sea replenishes it a bit. But it has been turned over so many time by fossickers the topaz in the area is getting increasingly scarce. The photos below are a results of a fair bit of effort at really low tides/calm sea. I ran out of ideas on where I could dig.  Much of the topaz I found came from digging an area missed by precious fossickers where the topaz was sort of enbeded in decomposing granite. Water as about waist deep. I spent a lot of time looking but really struggled to find anywhere else good to dig. Sieving the gravels near the diamond gully granite gravel beach would still yield a few but it represent little return for the effort.
I had a look around the Tanners Creek mine site. It still yields small topaz especially down stream from the mine site, but most are really small and go though a 1/4inch sieve.I'm am still really happy with my finds as there a quite a number of peachy/pink ones, a party very light blue/pink, and some nice blues. One green what probably won't cut. Even if you don't find any topaz it is still such a beautiful place around Mt Killicrankie, Stackies Bight, Old man Head, The Docks. If visiting I recommenced going for a walk up Mt Killicrankie as it is a really good track from the car park above The Docks. Compared to Mt Strzelecki it is a really easy walk with awesome views from so many points along the trail, not just the summit. Mt Strzelecki was really hard and do not believe the recommended times unless you are really fit and not taking photos along the way. Biggest stone was 85ct, the peachy pink one pictured 45ct. CheersMB