Black Spinel - cutting options and are large ones rare?

[Twapster]

Id love to know, other than cabochon what are some good options for black spinel? Also, going through my "stones that I put aside" found a pretty big one. I thought my 25 carat one was nice and wanted to get that cut, but forgot about the one I put aside which is over 100carat.....my gem scales only go to 20g!

What can I do with the big one....also makes me wonder what size spinel do others find? They are usually small in my experience but over 100carat seems quite large to me, or are they everywhere and common???

 

[Heatho]

G'day Twapster, never seen a hundred carat Spinel, pretty uncommon I'd say, though I'm sure they'd pop up that big now and then. I've seen a few 700ct Sapphire bombs though.

Pics please.

 

[Ryan1981]

hay Twapster, 100ct spinel wow.maybe emerald cut, most of the one ive seen are cut this way or princes cut,

 

[Twapster]

I've done the scratch test with a knife so far, doesn't make a mark. Looks just like the smaller 25carat one to the left, has the same sheen etc.

Does anyone think this is not a spinel?

 

[Salutations]

You sure they are not meteors?! Monsters!

 

[Twapster]

You sure they are not meteors?! Monsters!

Lol, im waiting for someone to burst my bubble......that's not spinel...that's the common Blackus Shinyus rock found all over NSW.

 

[Lefty]

They look like balck spinel to me Twapster, especially the smaller bit.

I've got a heap of the stuff from the Anakie field but most of it is small - I've never seen a 100 carat piece before. Got a few here that would probably go 20.

I've cabbed a few bits and I do think they look good cabbed, the stuff takes on a good polish. Haven't faceted any yet (still working on my first ever faceting job) but I have seen some cut into a kind of "checkerboard". A simple cut with no pavillion would probably look great in a man's ring.

 

[Sodabowski]

Twapsta, better keep your big spinels for decent cutting:

http://www.gemfrance.com/-Unite-?&p...typeId=1&nomId=511&isGallery=1&sort=reference

Here's a screenshot of that page for the future, check out the price:

That's 3500 Aussie dollars (minus VAT)

 

[rough2cut]

This is black spinel the largest is 168cts.According to that price of the cut stone and the fact ive got heaps of it Im retiring today.

 

[excalibur63]

Twapster, sure looks like Black Spinel (Black Jack) to me. I've got mountains of <5crt. and a dozen or so of 20-30 crt, but I have been told by a fellow prospector that he has "matchbox" sized Black Jack (although I've yet to see them as yet!!)

R2C, Nice large Specimens you have there, but from the photo, it more resembles something from the quartz family.

I had a muck around with a bit of Black Jack, and cut it in a SRB this is 3.6crt

 

[Guest]

Hey Mate,

Looks like the goods to me. Basic specific gravity test would get you a bit closer to an answer. I would imagine that the SG would come in around the Sapphire reading as they seem to hang out together in the creeks.

Also any small fractured chip of the specimen would be shiny at the break.

Also if you could get near a lapidary polishing machine apply some polishing to a corner, if it comes up like black glass your on the money. Does it have a good feel of weight to it compared to the size?

 

[Twapster]

I couldn't do an sg test because my gem scales cant handle it. Has a real waxy black sheen, maybe I should try some sandpaper on it to see if it goes like glass?

No chips in this one, my only concern is ive seen a lot of big spinel images and they have that "sapphire bomb" look to it like the ones Rough2cut has shown above, this one is not showing that splintering effect. Could it be something else? Sure looks like spinel to me but maybe there's another stone that has similar look?

 

[joe]

I couldn't do an sg test because my gem scales cant handle it. Has a real waxy black sheen, maybe I should try some sandpaper on it to see if it goes like glass?

No chips in this one, my only concern is ive seen a lot of big spinel images and they have that "sapphire bomb" look to it like the ones Rough2cut has shown above, this one is not showing that splintering effect. Could it be something else? Sure looks like spinel to me but maybe there's another stone that has similar look?

try and scratch it with another black jack and if you can't then it is a black jack mate.

 

[Twapster]

Did that too Joe, made a mark that wiped clean and no scratch...

 

[joe]

Did that too Joe, made a mark that wiped clean and no scratch...

hold on to them mate they will come up in price one day.

 

[Lefty]

This is black spinel the largest is 168cts.According to that price of the cut stone and the fact ive got heaps of it Im retiring today.

https://www.prospectingaustralia.com/forum/img/member-images/3816/1423358553_pic_1159.jpg

You are if you take it to France by the looks

 

[Twapster]

I've always felt spinel is underrated, and a bit of research indicated its undervalued. I've got no idea how common bigger ones are but either i've missed them when prospecting or they may be quite rare. I've had my head in the dirt quite a few times, plenty of small ones but not many over the 20 carat mark, over 100 carat I would think is starting to get up there?

 

[Sodabowski]

R2C nice big ones there! You could contact the owner of gemsfrance.com and see if he's up for a deal on these, he travels a lot and might make a trip to the land downunder. I met him twice at our local gem show here in Paris, nice bloke, sold me three small black diamonds for a very decent price back then. As he says on the page of that big Spinel, there really aren't that many black gemstones around, appart from diamond, tourmaline and spinel the choice is pretty slim (I wouldn't count in Jet since it's only 2,5 on the Mohs hardness scale).

I guess the main problem is the market, not the rough. Remember how things always work with gemstones: pile up and wait for it!

 

[Twapster]

Maybe need to ask Wal n Liz, im sure they have a wheelbarrow full of the stuff!

 

[Brumble-Gum]

Let me know if the piece on the 4th post is spinel Twapster.
I picked a piece identical last year like that,,,, maybe a little bigger.
I will be interested to see what you can do with it.
I am on site at the moment I will take a pic when I get home next week.