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Jewelry, Gems, & Minerals/Engagement Ring stone is loose after 2 months


A photo of my ring
A photo of my ring  
Hi Thomas,

My question is how to secure my center stone in my engagement ring. My ring is white gold with a 2 carat princess cut diamond in a cathedral setting with small diamonds in the band and on the sides of the setting.  It has a very high profile and is secured with 4 prongs.  After 2 months of wearing it, one day I heard it rattle.  I went to one jeweler who told me the only way to secure it was to redesign the entire ring and sink it down getting rid of all of the diamonds on the side of the cathedral setting.  Another jeweler we spoke with suggested just changing to platinum prongs.  Now I'm reading that platinum bends easier than white gold and the initial jeweler said the problem was that the gold bent too easily in the first place.  Now we are not sure what to do to decrease the chance of loosing the center stone.
I hope this picture is clear enough.  Thanks in advance for your advise and wisdom.

Dear Amanda,

First, thanks for the good photo. That does make a difference.

You have been given confusing answers and I do understand your concern.  First of all, knowing that I am going by the photo and do not have your ring in my hands, the suggestion of redesigning the ring and removing the stones on the cathedral section is ludicrous!  Whether the raised part of the cathedral design contains gems or not has little or nothing to do with the tightness of the central diamond.  Are the ends of the cathedral sections brazed (joined) to the center crown (stone setting)?  If so, sizing the ring down two or more sizes could in theory cause the sides to pull outward on the prongs but in reality the side stones would become loose and the cathedral sections distorted first. I simply do not see any relationship with stones in the cathedral section or the design of the ring and the loosening of your center stone.  As for the crown being white gold or platinum, the prongs appear thick enough to be strong, even with a stone as large as 2 carats.

Was the ring purchased from either of the jewelers you consulted? I say this because if they sold you the ring they would be responsible for tightening the stone unless there was obvious damage to the setting from a hard blow or some sort of repeated (and unnoticed) pushing action done over and over.  The answers given you make me think neither jeweler sold the ring initially.  I believe you would have mentioned any blow to the ring.

There must be other reasons and another cure for the stone becoming loose.

Please do not take this as any sort of negative statement on the choice of center diamond, that is, a princess cut.  You see, I believe the reason the stone is loose is likely because the stone IS a princess cut.  Some years ago when this lovely style of diamond cutting came onto the market, bench jewelers were having all sorts of problems firmly setting the stones.  With better crown design and improved methods to set this style of diamond jewelers are not so reluctant to set princess cut gems as in the early days.  Amanda, now you might wonder what in the world I am talking about.  This is it in a nutshell: The corners of a princess cut come together in a “point”, not the round edge of a round diamond or the flat edge of an emerald or radiant cut.  Depending on the cut of the corner, the point may be dangerously small or just thick enough to be safe and still be a corner. The danger applies to the diamond when the stone is actually set into the prongs. A thin corner has less strength than a slightly thicker one.  Jewelers will often tighten the stone just enough that they feel no movement and stop at that point.  With a round diamond, extra pressure may be exerted for added tightness.  Out of fear of damaging the diamond, a jeweler will often back off once the princess cut seems securely tight and extra pressure is avoided.  The stone may stay tight or over time may loosen as yours has done. The loosening comes from some very slight movement of the prongs and the delicate line between tight and loose in this setting style.

Can your diamond be tightened without changing prong settings?  That answer is yes.   However, from the point of view of the one doing the work, there is risk involved. The jeweler is not able to see the end of the corner and truly judge its thickness and lack of internal flaws. The jeweler is also not able to see how properly the prong was cut to accept the corner of the diamond.  Princess cuts require a particular style of cutting into the prong and that includes as best as possible a recess in the metal to keep direct pressure off the very tip of the corner.  This cutting to accept the diamond is called the “stone seat”.  If there is a bur or raised bit of metal inside that stone seat and if pressure on the prongs causes pressure to focus from that bit of metal onto a more delicate part of the corner, then a fracture can occur without warning.  To set and then later tighten the stone by the original stone setter is not a complete unknown but to another jeweler who is presented by a stone set by someone else, there are unknowns with the view of the diamond corner and the stone seat obscured.

If I were to tighten this stone, I would do it in a very particular manner. That is using pliers to gently squeeze adjacent prongs slightly toward each other then continue this around the ring. Each prong is moved first one way very, very slightly then moved back the other way the same amount.  Visually, this might be like “walking a piece of furniture into a corner” by moving one side in, then rocking and moving the other until the item is situated.  Pressure is applied sideways to the prong end and tends to bring the prong into the gemstone without direct pressure in that direction.  Amanda, this explanation may not make sense but it does work effectively.

The other options include a new prong setting or adding metal to the prong tips.  By adding metal, I mean brazing gold onto gold, not simply flowing solder on the prong ends.  The metal is then sanded and formed to show no work having been done and the stone should be tight. A new set of prongs would be needed only if you decided to change to a platinum crown.  The bending problem with platinum is not a problem.  A sufficiently strong crown would be chosen in the first place.  The “easy bending” of platinum is now your friend!  I am not talking at all about how strong and  sturdy are the prongs from the base to the top; a proper crown will be all that to begin.  The advantage of platinum in stone setting is that when it does bend, there is no spring back.  As you know, when you move a piece of metal to bend it, it will generally spring back a little (or a lot) in the direction where it was originally.  Platinum does not do that. When platinum is pushed into place, it stays right there. For this reason, platinum has a bending character superior to gold in holding stones secure.  With less effort and pressure on the gem, the metal of the prong tip is able to meet right up to the stone and stay there. This makes for a more secure setting when all else is done correctly.

I would not use the jeweler who suggested redesigning the ring to set a princess cut diamond or frankly to design a ring.  That jeweler seems to have missed some of the mechanics of what is happening in the first place.   As for the jeweler who suggested an alteration to platinum prongs, ask it they will take on tightening the stone as is and if not please clarify to you why they suggested platinum prongs.  That might be the place to have any work done.  Their answer will let you know if they understand using platinum.

Keep in mind, due to the nature of platinum it will become dull over time compared to white gold. The very nature that makes the metal great for stone settings is the reason! The surface tends to “burnish” or rub instead of being scratched away as with gold.  You will not see scratches on the shiny surface so much as an overall dulling of the shine with fewer apparent scratches.  Overtime, the platinum will tend to be rubbed down to the stone more than worn away and the prong tips should last some years longer than gold of the same thickness to start.

Amanda, you had confusing answers to start from the jewelers. I do hope I have been able to clarify the situation as I see it generally happening and have not added to confusion.  If for any reason you need clarification or have other concerns in this regard, please use the follow-up option to get back with me. Fair enough?  Also, please let me know if my answer helps.

God Bless and Peace.  Thomas.

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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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