Living in rural Northwest Ohio, with well water usage common in our area, we do see this issue occasionally. Some of our customers with exceptionally hard water experience this more than others.
One of our customers has a lovely emerald cut diamond engagement ring and matching wedding band that she brings in routinely for our bench jeweler to chemically remove the hard water deposits. Recently she brought in her ring and her near colorless diamond looked more like a M/N color and did not have much in the way of obvious dirt or minerals showing on the diamond.
The theory is that the iron (rust) has an affinity for diamonds and sticks to the surface and/or in the hollowed out area of the prongs that are designed to protect the corners of the diamond. With even a trace of dirt or minerals contacting the emerald cut diamond, the diamond will look noticeably tinted.
Here is what our skilled bench jeweler does to remedy this problem. He uses alternating baths in a pickle solution (heated acid bath) and heated ultrasonic along with a steam cleaner to help steam out any particles etc. This process takes patience, as it takes much more time and repeated cycles of the process than an ordinary cleaning.
But, when he was finished cleaning and refinishing her ring, it looked amazing!
As a home solution, you could try soaking the piece of diamond jewelry in vinegar, ammonia, or Dawn Dish Soap, then swish it around a bit and rinse with distilled or bottled water. This should help you keep on top of the deposits between treatments as well. Do NOT use bleach; bleach is very damaging to gold and will cause it to deteriorate and be brittle.
If you notice a change in color of your diamond, bring it in to us and we will be happy give your precious jewelry a ‘spa treatment’ to remove the mineral deposits and brighten it back up. Our full-time bench jeweler has more than 38 years of experience and does all of our work on-site. We'll take excellent care of your treasured items and have them looking like new. Learn more about our expert jewelry repair here.