Need advice on how to cut this Rough Spinel

[iambernard45]

Hi PSer! Firstly, I would like to briefly introduce myself as it is my first time to create a post here. My name is Bernard, I have been interested in gemstone for 4 years and started collecting them. I often check out other member posts and have been enjoying reading them. Enough about me, I don't think you are interested in other unimportant stuff about myself . Let's get back on topic.

Recently, I have just got my hand on a lovely rough Pinkish Red Spinel. The size is 29.88ct. I have totally zero experience with rough and bought this just purely attracted to the sweet color, what I would call an impulsive buy. I showed to a few friends and they are concerned with the cracks by side, color as well as stone shape. Ok, here are some of the shots I take. Hope I can get some insights on this piece before cutting. Any input is well appreciated, Thank you very much.

AND Here's the video
http://youtu.be/15xaVCyTgZw

 

[ephsea]

Wow what a wonderful color - it's breathtaking!

 

[LoversKites]

Unfortunately I know nothing about faceting rough but wooow that colour is pretty!!

 

[iambernard45]

Thanks... Ya, I think it will turn out sweet! Or rather hoping it will

 

[mastercutgems]

Hello

It looks like a very nice piece of rough...

If it were me that was getting ready to cut it; I would do as you are doing and shine the light in to see any fractures or flaws. I take a sharpie or similar very fine point felt marker and draw out my inclusions/fractures. Then I look at the shape; depth to width ration of 75% to get a brilliant cut. Then I decide on the shape and unless it is some odd-ball shape I usually let the gem dictate the cut. It looks like an oval or pear from the crack and original shape; but all that can change when you outline the issues.

I hope that helps; some

Good luck on it and I would like to see the finished product as it looks like it has the potential of being a very stunning gem.

Most respectfully;

Dana Reynolds
ASG Certified
Supreme Master gem Cutter
#96CGE42

 

[Michael_E]

That's a nice looking rough! While shining a light into it can show large reflective fractures, anything small or fuzzy just won't show up this way. If you submerge it in a little clear jar of oil it can help to remove some of the fuzziness of the outer surface. For the best look into this stone I would strongly suggest polishing a couple of flats onto areas which will be removed during cutting later. If the stone has an obvious place to locate the table of the stone, then polishing this will give the largest window into the interior as well as locating the table, should the interior be clean. In doing this you can look into the interior of the stone with a loupe and see exactly what sort of clarity issues you may be facing and decide how best to avoid those issues. This can be very important and even change your mind about the shape that it should be cut into, (by showing a patch of micro inclusions on one side for instance). I look forward to see the finished gem!

After looking at your video, I would also suggest measuring that stone very carefully and maybe even taking photographs from various angles. Using the photographs as a background in your favorite CAD program will allow you to overlay those images with different stone shapes and sizes so that you can maximize the face up size of the stone with the most popular and salable shapes, (no point in cutting a shape that is hard to sell...assuming that eventual sales is your intent). The other benefit of using this approach is that it can allow you to customize the cut design and even render different designs in order to obtain the most attractive stone possible.

Michael

 

[velouriaL]

Nothing to add except very cool to hear about process from Dana and Michael! Thanks, guys!

 

[iambernard45]

Thank you Dana and Michael. I would love a cushion shaped but i think it is not a wise choice for this rough. As Michael suggest, after marking the flaws, the rough shape is more like a /==> this shape, does not look too good.

I have tried submerge the stone into a bowl of water and shine light into it, I can see a small burst that I should mark it out of the final shape. Polishing a small flats around the expected table area sounds like a good idea, will have to do it and analyse for any unwanted inclusions.

Thank you for the inputs. I am expecting a perfectly cut oval shaped with at least 12 ct size. I will be meeting the stone cutter man in 10 days time, wish me luck all!

 

[Mico]

I can't wait to see how this turns out!

 

[chrono]

Looking forward to how this piece of rough turns out; I think even 10 ct as the final size is being overly optimistic. Good luck!

 

[iambernard45]

Thanks guys, will keep you posted..
Hi Chrono, will it really be wasting that much weight? If so, I might have spent too much for this rough..

 

[chrono]

30% yield is considered very good. Most lapidaries get around 20 - 25%; depending on luck, it could be as little as 10% (if there is an inclusion in the way or it cracks) or as high as 35%.

 

[iambernard45]

Ouch, that is pretty low yield. Thanks, this would make me think thrice before buying another rough.

 

[chrono]

Ouch, that is pretty low yield. Thanks, this would make me think thrice before buying another rough.

I am sorry. This is why many of us purchase already cut stones. We leave it up to the expert lapidaries to figure this part out.

 

[iambernard45]

Yeah, hopefully it turns out well.

 

[minousbijoux]

Bernard:

That is a gorgeous piece of rough and whatever size it ends up being, it will be beautiful. I just wanted to state the obvious and say that I hope you will have a dialogue with whomever is cutting your rough so that you are given choices and you and the lapidary can decide the best option together based on color, desired shape, and rough conservation. Good luck - can't wait to see the finished piece.

 

[chrono]

Bernard:

That is a gorgeous piece of rough and whatever size it ends up being, it will be beautiful. I just wanted to state the obvious and say that I hope you will have a dialogue with whomever is cutting your rough so that you are given choices and you and the lapidary can decide the best option together based on color, desired shape, and rough conservation. Good luck - can't wait to see the finished piece.

+1. I, too, am looking forward to the end result of that very promising looking spinel rough.

 

[OTL]

I really like your avatar ring, can you post a picture of it? What is it? Spinel and tsavorite ring?

 

[iambernard45]

Thanks guys, will post some pictures after finish cutting.

My Avatar pic is a Padparadscha Sapphire set with Diamond/Tsavorite. Here is the picture, but I have already sold that piece

 

[minousbijoux]

Thanks guys, will post some pictures after finish cutting.

My Avatar pic is a Padparadscha Sapphire set with Diamond/Tsavorite. Here is the picture, but I have already sold that piece

Lovely - the padparadscha is beautiful.

 

[OTL]

Amazing! That is really one of a kind beautiful piece of jewelry! Rare to see. Thanks so much for posting it.

 

[Mico]

Wooow

 

[RedSpinel]

Obviously that stone has been rubbing up against other stones in nature for a very long time, and its become near impossible to see inside it for clarity and to figure out how best to cut it. But as a non-gemstone cutter, I always wondered how this type of gem gravel rough is evaluated, considering you cant see whats inside?

Can they maybe polish the outside smooth to the point where the inside can be seen? I wouldnt think you'd lose any weight by external sanding/polishing. If the stone was generally mostly clean, you should then be able to see inside. If thats now how its handled, how do they figure it out when you cant really see whats inside?

 

[chrono]

Red Spinel,
If shining strong bright light does not allow you to see into a piece of rough, then the material is too dark or too opaque to begin with. I think sometimes, a bit of the outer "skin" is polished or smoothened to help look into the material without much weight loss.

 

[JewelFreak]

The padparascha & its setting are beautiful! Good luck with your spinel -- I'm looking forward to seeing the results. Interesting responses you've had.

 

[cm366]

Obviously that stone has been rubbing up against other stones in nature for a very long time, and its become near impossible to see inside it for clarity and to figure out how best to cut it. But as a non-gemstone cutter, I always wondered how this type of gem gravel rough is evaluated, considering you cant see whats inside?

Can they maybe polish the outside smooth to the point where the inside can be seen? I wouldnt think you'd lose any weight by external sanding/polishing. If the stone was generally mostly clean, you should then be able to see inside. If thats now how its handled, how do they figure it out when you cant really see whats inside?

A bit of 'skin' is sometimes polished (called a window), usually on the surface that was going to be the table, so there's no loss to the final weight and the best chance to see inside the stone. However, polishing a window is a fundamental alteration to the stone itself - beofre it had pretty colour and unknown inclusions, so it sells as a risky piece with potential for $$$. Now anyone holding it can see those inclusions, so the value may change up or down. What that means is, you can polish a window on stones you own (and many cutters would do so on any valuable piece of rough before diving in), but not on stones you're considering, or that you might want to return.

Not specifically related to spinel, but there's an entertaining story from RIchard Wise on that risk in buying rough here:
http://www.gemologyonline.com/jade-heart1.html

Note: this is not a forum link, only a story

 

[minousbijoux]

Not saying it would work for spinel, but on lower RI rough, faceters can - and often do - use refractol.

 

[iambernard45]

Shining light on the rough can see through what is inside. The last few pictures with lights, cracks are shown. This rough is pretty much clean but the shape is a little off, so may need to waste quite a bit of carat to get perfect facet. A few more days and I will meet up with the stone cutter master, my first time to invest on rough stone and it has been very interesting experience indeed.

 

[minousbijoux]

I just checked to see if you had spoken to the cutter yet, and realized you said it would be ten days before you did. Sigh. Ten days is just not going to be fast enough...

 

[upcyclist]

Thank you Dana and Michael. I would love a cushion shaped but i think it is not a wise choice for this rough....

....I am expecting a perfectly cut oval shaped with at least 12 ct size.

Of course, if you want this stone set in a specific piece, you can ask the cutter to cut it into a cushion. It won't weigh as much as the "ideal" shape for that rough, but in the end, that is your choice. The cutter can only make recommendations, and you're the client.

And as others have said, that's probably too optimistic for a finished weight. I often use 20% for a couple reasons: 1) it's more conservative, and therefore I'm less apt to be disappointed when I finish cutting it. 2) it makes the math easy--you take your rough weight in grams (yours is 5.98g), and that becomes your estimated yield in carats (cuz there's 5 carats in a gram).