The short answer is "NO!".
But, we do understand that this is a huge concern for many people when dropping off their jewelry for repair. The sad reality is that the jewelry business is like all other businesses, in that there are some good people and some not so good people.
So let's take a look at how you can protect yourself against this possibility. But, first, it's important to understand some things.
Removing and resetting a gemstone, whether it be a diamond or colored stone, is not an easy or quick thing to do. If it's set in a bezel or if it's flush set into the ring then the work to remove and reset a gemstone would be so intrusive and destructive, it would be very difficult to hide. Prong set gems would be the most vulnerable, but, even then, you must pull back the prongs, without doing damage, reset a stone that has virtually the same proportions, then remove any marks on the prongs to cover your tracks. Although not very difficult for an experienced craftsman, it does take a considerable amount of time in addition to numerous tools.
Another thing to understand, is that when you leave your ring, it will be in a "worn" condition- scratched and, at least, somewhat dirty. When you pick up the ring, it will be polished and clean. In other words, it will look different. If you were concerned to begin with, this alone can cause alarm.
The best course of action, when there are concerns, is to discuss them when you bring the ring in initially. This will provide an opportunity for both of you to take a look at the ring and gem(s) to get measurements and to take a close look to see if there are any easily recognizable aspects to the gemstone, such as inclusions (what we like to refer to as 'birth marks') or chips. Using a jewelers loupe (magnifier) to look at your jewelry can take a little practice, but it's well worth your time and can often resolve any concerns you may have.
We always recommend that jewelry should have an appraisal and be insured. If you do have an appraisal, then, hopefully, it will have the imperfections of your diamond mapped out for you. If this is the case, then you should be able to have your gemstone verified before and after having it worked on to insure it is yours.
Another option is a laser inscription. There are a number of laboratories that provide a service that, using a microlaser beam, can inscribe diamond report serial numbers, company logos, and text messages on the girdle of a diamond. If your diamond is inscribed with a certificate number, make sure to note the location of the inscription so that you can find it again when the diamond is returned to you. Mention the inscription to the jeweler; this will not only alert the jeweler to the fact that you are aware of this security feature, it will also insure that when setting or repairing the ring the inscription is not inadvertently obscured or damaged.
Of course, there is one more 'bullet proof' way to alleviate your concerns and anxieties- Watch the goldsmith set your diamond. Here, at Jewelry Doctor, you can let us know ahead of time of your concerns and what work is needed to be done, and we can (in almost all cases) do it while you wait and ..... watch. A good example of this occurred recently with a 2 carat diamond a lady wanted set into a new ring. She brought in the diamond, so we could measure it and determine the proper type and size of the head. She then left with her diamond and we ordered in the head, polished it, then soldered it into the ring and got everything ready for setting the diamond. We then called her up, set up a mutually convenient time, gave her a chair and she watched as our goldsmith set her diamond.
A true story- Many years ago, when we were still located in Lansing Mall, a young lady came in to have some work done on her engagement ring three days before her wedding. Her ring was examined and we could see that the ring could be worked on, but only if we removed the stone first...... because it was a cubic zirconium. The truly unfortunate thing was that we were quite certain that she thought it was a diamond. It was an awkward situation.
Obviously, we didn't want to take it in with any misunderstanding, so the situation was gently explained to her. She was visibly shaken and explained that, no, it was a geniune diamond that she received from her first marriage and she had an appraisal for over $5,000.00 to prove it. She was asked if she had her ring worked on recently, and she said 'yes' and told us where it had been taken. We explained that we thought she should go and have a talk with them and hoped that it had been an innocent mistake.
As you can imagine, we were very curious about the outcome of this conversation, so we were pleased and surprised when she returned about an hour later. Still shaken and fighting back tears, she explained that, yes, the diamond had been switched for a cubic zirconium. At her fiance's request.
We would have loved to hear his explanation when she got home.