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Jewelry, Gems, & Minerals/Not a Ceylon sapphire?


QUESTION: I have just seen a response to gave to a lady regarding a chipped sapphire in her engagement ring and would really value your input on my ring please. A few weeks ago my husband treated me to a beautiful ring containing a 1.58 carat heart-shaped Ceylon sapphire in a diamond surround setting. The ring was purchased from one of the long-established jewellers in Hatton Garden. Like your previous enquirer, I have noticed that there are now at least three little chips on the edges of the sapphire; not visible by eye but clearly visible through a jeweller's loupe. This damage was definitely not there when the item was bought but I have treated the ring very carefully and have no idea how it has arisen. My concern is that the stone is not a Ceylon sapphire but a softer stone like tanzanite. This is rather ironic since the ring was purchased for everyday wear to protect an earlier tanzanite purchase. I was thinking of returning to the jewellers to seek their advice but is there an obvious way to determine whether the stone is in fact sapphire or something else? Any help would be greatly appreciated. The ring is so beautiful but I am now frightened to wear it, in case more damage is inflicted on it. Thanking you in advance for your assistance.

ANSWER: Leslie, in my experience, a tanzanite would more quickly be scratched or abraded than chipped although both sorts of damage are very possible.

There are certain characteristics of tanzanite which a qualified jeweler may use to rather quickly separate tanzanite from sapphire.  Some of these tests have to do with refraction, dichroism (two colors depending on direction of viewing) or trichroism which is the natural state of tanzanite and specific gravity(mass in comparison to water of the same volume).  All but the specific gravity may be checked in most cases with a mounted gemstone.  

Specific gravity of sapphire is 3.98-4.02 and tanzanite is 3.2-3.4.  Generally, we consider this as "weight" and for the same size gemstone a tanzanite weighs less and for the same carat weight a tanzanite is larger than a sapphire.

Unfortunately, these are tests you cannot do at home without certain equipment.  There is a filter said to help identify tanzanite by showing the stone in a gray color when viewed through the filter. There is a similar glass filter called a Chelsea Filter used with emeralds, showing red through the filter when the green of the emerald is removed from the visible spectrum.

Lesley, what is best to do?  Is there a jeweler closer to you than Hatton Garden? If so, give them a call and ask if they can check the stone for you and if there is a charge for that. Otherwise, it is a drive back to London to where the ring was purchased. I would not expect the sapphire to chip soon after purchase when worn with care, as you say you have done. From your previously purchased tanzanite you are certainly aware of care needed for jewelry.
The jeweler can look at the stone and if sapphire as it was sold to be, a magnified and properly lighted microscope look may reveal any internal flaws unseen by the eye. It is not common but possible such flaws could lead to uncommon damage. In that case, I suspect the jeweler would replace the gemstone with an equivalent of equal beauty.

I am sorry I cannot be of more service. Unfortunately I have heard of gems being incorrectly identified by home methods without the experience to read tests properly.

Gert back with me if need be. God Bless and Peace.

---------- FOLLOW-UP ----------

QUESTION: Hi Thomas,
Thank you so much for your help and prompt reply. I have been to an independent local establishment who confirmed that the stone was a Ceylon sapphire. With this knowledge, I then returned to the jewellers where I purchased the ring. The owner was extremely defensive and basically said the damage was down to my mistreatment of the ring although I know I have always taken great care of it. He grudgingly kept admitting that he "didn't know what to say", "couldn't see what had happened" and "that he had never known this to happen before". I felt that I achieved nothing from the exchange other than more distress. He said that sapphire was not indestructible and that I couldn't expect it to be. When I commented that it was second on the Moh's scale of hardness to diamond. He said that they were not as close as the scale suggested and diamond should be 100!
What I would appreciate from you is some idea as to the likelihood of the damage happening so quickly after purchase; three chips and a couple of nicks on the edges and top surface of the stone? If there is a fault with the stone, is there any specific defect which might result in such chips and damage please? He only looked at the ring through a standard Jeweller's loupe and said it was perfect - no striations etc. I've attached a photo of the ring, prior to the damage. Your expertise in this matter would be greatly appreciated as I really do not know what to do and am so distraught at how things have worked out.  

Many thanks and God bless.


Dear Lesley,

I believe the strongest support you have that the gem should be replaced is the statement by the jeweler who sold the ring in the first place:
…he "didn't know what to say", "couldn't see what had happened" and "that he had never known this to happen before."  Would he admit that if he had never seen this before that perhaps the particular sapphire  does indeed have more brittleness than should be expected by a customer desiring a durable gem?  You know that a sapphire will wear to some extent over a long period of time but is known for more durability than most other gem stones.  You must be also fully certain the chips were not present when the stone was purchased.

Certainly a sapphire is not so durable as a diamond and he is correct that the difference in #9 and #10 on the Mohs scale is greater than the scale would make a person think. The scale is relative, comparing which will scratch which, starting at the top and working down to the bottom each stone with a higher number will scratch those with lower numbers. That is all the scale says.  Since much of the everyday abrasiveness in “dust”, etc., is made of quartz and that is #7, general wear will be low compared to gemstone below #7, stones such as tanzanite which is #6.5 generally.  In absolute hardness, the scale would be 1 to 1600, with sapphire at 400 and diamond at 1600.

Keep in mind this important consideration: Hardness is not the same as brittleness.  How brittle is glass compared to perhaps a plastic material? Which is harder, a plastic dinner plate or a glass one? Glass is certainly harder. Which will chip?  You know the plastic plate is unlikely to chip but provide care with the glass plate to avoid chipping it!  

Sapphire will chip and so will a diamond but to chip excessively for no apparent reason is not within the character of sapphire. This is brittleness being considered and not hardness.  There is evidence that heat used to improve color and perhaps clarity in sapphire and ruby will in some cases render a stone more brittle than should be.  I have set sapphires into difficult mountings with no problems whatsoever and then done a simple bezel setting only to have a steel burnishing tool appear to scratch the stone. Under magnification, the scratch is a series of minute chips which should not have happened.  I suspect that stone had become brittle from the heat treating process.  The same may be true with your gem.  This is not going to happen every time to every heat treated sapphire. But, “ he had never known this to happen before” could be a result of an unpredictable brittleness in your Ceylon sapphire.  

I honestly do not know how to prove this as a cause, if indeed that is the cause.  A thorough examination at high power with a gem microscope might show minute damage beneath the surface of the stone in areas where the prongs are pushed to the gem or on facet faces near the prongs.  Depending on technique used by the stone setter, a file is often used to shape the edges of the prongs prior to final buffing. Then a small wheel is used to remove file marks and all is polished and done. With a brittle gem, the file may run along a junction of one facet face with another and on that edge may be a tiny chip or even tiny fracture just beneath the surface.
Possibly the jeweler you visited who is not associated with the situation could take a very close look again, at the gem surface and just below the surface internally for any tell-tale signs.
You do not want to ague from a gemological point of view because you are at disadvantage.  You might appeal to the reputation of the store and that this happening IS unusual and certainly not a common event.  The early damage is not at all what would be reasonably expected by any customer purchasing a sapphire from that business and not what the jeweler admittedly “had seen before”.  Something is amiss and I believe that calls for a replacement of the stone.

Does the business value your opinion of how they conduct business? They should.  You might ask them.  Do they value repeat business?  This will be taken as a threat but smooth it by asking if all customers are treated in this fashion when there is a problem.  Are they willing to do what you consider is the “correct action” in the situation?  As a last recourse, if they are convinced it is not fully their responsibility are they willing to compromise on a replacement stone?

Just for some back up on my statements about brittleness of heated gemstones, here is a website you might want to visit. (Remember, there is really no proof of this being a cause in the chipping but is a reasonable consideration.)  There are a series of forum postings and the most valuable being that one by “china-sapphire” a short scroll down the page:

Lesley, I do not know if my answers have helped one bit. I hope some value is there.  Please let me know how it goes or get back if you need too otherwise.

God Bless and Peace.  Thomas.          The nice and lovely photo is appreciated.

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Have a question about jewelry repair or working with precious metal jewelry and gemstones? For many years up to December 31, 2010, I was a working professional bench jeweler, involved everyday with setting stones in mountings, designing and making jewelry, repairing and limited custom manufacture. If you work with jewelry as a hobby or as a profession, I might be able to help. I deal with the retail business, not mass production. Ask privately if you wish. See the box for that: It keeps your question between us. Please DO NOT ask MAKER'S MARKS, but metal quality marks are fine to ask. Please DO NOT ask diamond prices. See a gemologist for that.


I have extensive experience in design, service and making of jewelry. I deal mostly with precious metals and gemstones but work with many materials as needed and usable to create an artistic design. My experience also includes freelance photography and photographer of jewelry and similar items for a former employer and individuals. Design of custom items requires reading the desires of the client and being clear on what can be done within that framework...then fulfilling the transition of idea to reality. Effective communications is essential in a working designer/producer and customer relationship.

Education is English/Physics! Started in human resources, to advertising, to, what a road. I have had formal training in jewelry work and many shared experiences with top grade jewelers. We just never know were we will go or be. Follow your best, your dreams, with some discretion! Don't let the work tear up your body along the way as it has mine.

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