Blue Sapphire, field shopping information

[Lee Little]

Greetings,
When shopping for a Sapphire of fine quality in a market place there will be many factors to consider but this will only touch on a couple of the factors as complete information could fill a few books.
Usually a fine quality stone will have little or no inclusions visible even when you look with 10x loupe. The first concern when there are no inclusions visible is that it may be a synthetically made Sapphire rather than a Sapphire mined from the ground. Synthetic gems are usually valued much lower than naturals. That is why it is often comforting to find a tiny natural inclusion that we recognize or some color banding that has a 120 degree corner. This type of banding is only seen in a natural Sapphire so if we are sure that there is color banding with this type of corner then we know we are looking at a natural Sapphire, however, look at the attached picture.
In this stone we can clearly see the color banding with the 120 degree corner. Many times this banding will be much lighter and harder to see but I selected this stone so that it can be seen in a photograph. Even though we now know we are looking at a natural Sapphire, we must check the girdle of the stone for a seam. This will require at least 10x magnification. On this particular stone there is a seam barely visible under 10x as this stone is an assembled stone, also known as a doublet. The crown is natural Sapphire and the pavilion is a synthetic Sapphire and they were glued together as rough then faceted so that the seam is hidden on the girdle. This type of stone is designed to fool the gem buyer. Often the crown has lighter banding than this as they want us to believe that we are holding a very fine quality natural Sapphire so we will pay them far too much for their assembled product. I would advise to make a close inspection of the girdle of every Sapphire before buying it, even from a trusted local jeweler as this product has made its way into many fine shops without being detected by the gem buyer of the store. Best regards, Lee

 

[kenny]

Thanks Lee.
Great info!

I knew they glued together opals, but not sapphires.

 

[minousbijoux]

Lee:

Thank you so much for this information. If we could have you, other vendors - or even knowledgable consumers - continue this thread with added pieces about treatments, cut and color, we could have a great pinned thread about sapphires. For example, we could add a section on diffusion, a section on heat vs. none, etc.

Personally, I find your information very helpful, and until your post, I would never have thought that a sapphire showing zoning could possibly be a doublet - just would never have thunk it!

 

[Pandora II]

People will glue together anything that can be glued.

I've seen fabulous looking emeralds that are a beryl top, green glue layer and then a glass or even beryl bottom. The ones I have seen were set in antique jewellery (where the girdle is covered and it would not be possible to remove the stone without destroying the setting) - they are very hard to spot.

Garnet-topped doublets are also very common. Your eye will see the colour on the base of the stone so a piece of green glass with a slice of red garnet on top will look like a lovely emerald and a piece of blue glass with garnet on top will look like a spectacular sapphire.

They are not so common these days because synthetics are so readily and cheaply available - but are worth looking out for in antique pieces. There are easy giveaways if the stone is loose, but not see easy when they are set.

 

[chrono]

An excellent educational post. Having pictures is also incredibly helpful. Most novice gem buyers probably aren't even aware of doublets and triplets. If there is anything that can be done to cruddy stones to improve their appearance, and therefore its value, it can and WILL be done. Thank you!

 

[beau-wy]

I will add that even buyers of rough for commercial cutting are not safe! I sent a parcel of rough Australian sapphires to a formerly trusted Bankok cutting house. I sold a pretty blue round to a GIA GG, and was shocked and embarassed when he discovered it was a synthetic spinel crown/natural sapphire doublet. He was a good sport, believed me ... and wanted to keep it for his collection anyway. After verifying it was a doublet through an independent third party, I refunded his money and let him keep it.

It was the only one in the parcel, however, another gem from the parcel of cut goods was a tourmaline. I had often suspected some substitution was occurring, but never thought they would substitute anything but the same gem variety. That was School of Hard Knocks lesson 537 or so ... have not used Bangkok cutters since 1995 as a result.

 

[T L]

Thanks for the info Lee.

 

[SB621]

No way I didnt' even know that was possible.....

I need to get a magnification glass thingy or whatever it is called. I'm so curious now.

 

[PursuitOfBling]

Ridiculous. So frustrating that buyers and vendors have to deal with this sort of malarkey. Fantastic thread btw, very informative, and appreciate the heads up.

 

[Enerchi]

Thank you! I did not know they could combine natural and synthetic. Again, just thought that was an opal only thing.

 

[T L]

Thank you! I did not know they could combine natural and synthetic. Again, just thought that was an opal only thing.

They do it with emeralds too, and I imagine ruby.

 

[movie zombie]

wow. another minefield to navigate in the color stone world.

 

[T L]

wow. another minefield to navigate in the color stone world.

Yes, we have diffusion, coating, heating, irradiation, filling with a multitude and amount of substances, composite, and doublets, triplets with part synthetic and/or part natural stones. This doesn't even include the myriad of synthetics out there with and without believable inclusions.

With emerald, they usually sometimes splice a very pale piece of natural beryl or light green beryl material and put it on top, put some green material in between the two pieces, and voila, you get what looks to be a beautiful natural stone to a novice.

 

[movie zombie]

[quote="TL|1333471543|3162519.......With emerald, they usually sometimes splice a very pale piece of natural beryl or light green beryl material and put it on top, put some green material in between the two pieces, and voila, you get what looks to be a beautiful natural stone to a novice.[/quote]

and therein lies the rub: a novice may pay big $'s thinking s/he got the deal of the century....when in fact they may have overpaid and would have been better off buying green glass.

 

[T L]

[quote="TL|1333471543|3162519.......With emerald, they usually sometimes splice a very pale piece of natural beryl or light green beryl material and put it on top, put some green material in between the two pieces, and voila, you get what looks to be a beautiful natural stone to a novice.

and therein lies the rub: a novice may pay big $'s thinking s/he got the deal of the century....when in fact they may have overpaid and would have been better off buying green glass.[/quote]

Very very early in my gem collecting, I learned that the hard way. Fortunately, I bought the doublet from a reputable vendor who refunded my money. His associate sold me the stone, and didn't tell me it was a doublet. For a very short time (until I took it to a gemologist), I too thought I had the deal of the century. *sigh*

 

[Kismet]

Very interesting information. Thank you! Do you happen to have a picture of the girdle seam?

I tried looking at my new (antique) sapphire ring with my loupe but realized that I need more than 10x magnification because my vision is the pits. Couldn't see 120degree banding ether.

 

[chrono]

The 120 degree banding will be very difficult to spot in most sapphires with a 10x loupe because of the darker tone. Providing additional lighting and having a better powered microscope will go a long way in this case. I guess for those on the road without this equipment (only a 10x loupe), having experienced and trained eyes can spot this banding?

 

[Lee Little]

Very interesting information. Thank you! Do you happen to have a picture of the girdle seam?

I tried looking at my new (antique) sapphire ring with my loupe but realized that I need more than 10x magnification because my vision is the pits. Couldn't see 120degree banding ether.

Hi Kismet,
I tried to get a shot of the seam but it was not clear enough, I will try again next time I am taking pictures. Best regards, Lee

 

[Pandora II]

Sometimes the seams aren't at the girdle - I've seen stones where the meet is part way up the crown - you look for differences in lustre on the facet faces.

We were trained to have a mental check-list of things to run through with every stone - stops you getting carried away by the colour/price/whatever and concentrate on the hard facts. Every stone we saw in class had to be drawn, labelled and all inclusions/features - surface and internal mapped, drawn and described. After 2 years of doing that it becomes second nature - although things still slip through the net. A friend recently came back from a buying trip with a beautiful purple sapphire - I was having a good look at it and asked if he'd noticed the surface reaching fracture, then provided gin while he beat his head on the table for not checking properly... he'd been concentrating on internal inclusions looking for synthetics and signs of high heat and forgotten to look hard at the surface.

Here are a couple of photos:

The first is a garnet top on a red paste base - you can see the difference in lustre on the facet surface.

The second is a ruby doublet - green sapphire on the crown and red synthetic ruby on the bottom. Your eye will automatically see the colour at the bottom so the whole stone will look red and you won't see the green. If the stone was set so that you couldn't see the girdle you are relying on spotting the inclusions indicating it to be a composite. The RI will be that for ruby given that the top is sapphire.

These are not particularly subtle examples.

 

[Kismet]

Thanks for the pics and the information, Pandora. I'll have to dig out the microscope when I get home.

 

[Pandora II]

You won't need a microscope - just a x10 loupe - or even naked eye.

 

[Lee Little]

OK, I got a couple of shots of the smoking gun, the seam on the girdle of the blue Sapphire doublet. This seam is not easy to spot as you can see by the pictures. This is an 8x6 stone so these pics are huge. I cherry-picked these two as showing it the best. Note the stone is upside down in these pics to get the light to help see the difference between the two materials.

Best regards, Lee

 

[chrono]

Thanks; I can see the seam clearly in this magnified pictures. What is the approximate magnification of these pictures? I was wondering what it'll look like under 10x, as though we are looking through a loupe.

 

[Lee Little]

Good question Chrono, I took these with a Dinolite Microscopic camera and there is no indicator as to the magnification but I would guess these are at least 20x, perhaps 40x? With 10x I had to study hard to see it. That is why I was inspired to post this, I had seen others that were quite easy to see but this one came from an entire parcel of well made frauds. Best regards, Lee

 

[Kim Bruun]

Very educational - and depressing. Like movie zombie said, another minefield to navigate. We've got glass-filled rubies, coated tanzanite, be-heated sapphires, emeralds that are not only treated with oils, but with coloured oils to improve colour. And then there's the whole range of synthetics...

Actually, doublets have been around for decades - I just thought they were easier to spot.

 

[Lee Little]

You are right Kim, they are really making it interesting these days, LOL. And yes, doublets are certainly old news, I just thought they had not been given enough attention to bring up the level of awareness and some people are paying thousands for a sneaky creation like this with very few warnings out there. Best regards, Lee