When making a sale, do you advise customers about proper care of gems and jewelry? You should, because it’s good business. If the jewelry continues to look good long after it leaves your store, others will notice, resulting in valuable word-of-mouth

advertising. In addition, since some cleaning methods can harm gemstones, providing care instructions will reduce the risk of damage later on. And, of course, offering advice on care reinforces your image as a professional.

Do-it-yourself cleaning. Several home cleaning methods are available to consumers. One that shouldn’t be overlooked is boiling, which can be very effective for cleaning certain types of stones. Bench jewelers boil jewelry as the last step in the cleaning process to remove the polishing rouge and dirt. But because not all gems can be boiled, it’s important to make sure you’re giving your clients accurate information.

The following gems are usually safe to boil: diamond, ruby, sapphire, garnet, spinel, jade, topaz, tourmaline, quartz, and chrysoberyl. However, some will not take thermal shock, which can occur when a gem is subjected to an extreme and rapid temperature change. This can happen when it’s dropped into a pot of boiling water. The sudden change in temperature can cause internal fractures in some gems, such as garnet or tourmaline. In rare instances, a gem can possess an inclusion that can be considered potentially dangerous. The jeweler should examine the gems under magnification. When in doubt, don’t boil.

To boil jewelry safely, start with a pot of water and a strainer. Place the jewelry in the strainer and then put the strainer in the water with a small amount of detergent of any kind. (Both laundry and dishwashing detergent will work.) Bring the water slowly up to a boil (to avoid thermal shock) and let the jewelry cook for 10 to 20 minutes. If it’s extremely dirty, you may need to use a soft brush around the stones.

Ultrasonic and vibrating cleaners are also options. Ultrasonic cleaners send ultrasonic waves through water that will loosen any dirt and clean the jewelry. Professional models range from $150 to more than $3,000. Most laymen use simpler vibrating cleaners. These also send vibrations through water, so the concept is the same. However, they don’t use ultrasonic waves and thus are less powerful – and less risky in the hands of nonprofessionals. Most vibrating cleaners retail for less than $25.

Some jewelers sell vibrating cleaners, or even give them to their customers as gifts. Barry Block of The Jewelry Judge in Garden City, N.Y., is a full-time appraiser who sees about a dozen clients each day. He advises them on care and then offers to sell them a vibrating cleaner. About five customers per day purchase the cleaner, according to Block. Clients are thrilled with the added instructions for care he provides.

It’s inadvisable to sell true ultrasonic cleaners to the public, however, because these machines can be dangerous if not used properly. Many stones, such as emerald and tanzanite, are unsafe for ultrasonic use. They may fracture internally from the vibrations and can cause some emerald treatments, like oil, to come out. In addition, an ultrasonic cleaner can shake loose-fitting gems from their settings. If your trade shop uses ultrasonic cleaning, check gems before and after the process to ensure that they are tight in the setting.

Ruby, Sapphire, & Diamond

Ruby and sapphire can withstand rigorous cleaning procedures. They usually can be boiled safely and are safe to place in an ultrasonic cleaner. Corundum gems have a hardness of 9 on the Mohs scale and are reasonably tough. Diamonds, of course, at a hardness of 10, pose little concern in the cleaning and care arena. Boiling and ultrasonic cleaning of diamonds are considered very safe, with few exceptions. For example, prolonged ultrasonic cleaning of a fracture-filled diamond may damage the enhancement. Before using an ultrasonic cleaner, check with the manufacturer to determine if the diamond has been treated.

Emerald

Emeralds aren’t tough at all. Their hardness on the Mohs scale – 7 1/2 to 8 – is adequate, but because they usually are included with surface-reaching fissures, they often are oiled or subjected to other treatments. These enhancements make it unsafe to boil emeralds or place them in an ultrasonic cleaner. Not only will the treatment come out of the gem, hurting its appearance, but also some heavily flawed emeralds can break into pieces in an ultrasonic cleaner.

Low-frequency vibrating cleaners are usually safe for emeralds when used for only a few minutes. Block demonstrates this by holding the emerald or other jewelry in his hand, which he then puts into the cleaning machine. “If it doesn’t hurt your hand, how can it hurt the jewelry?” he tells customers.

It may be safe to expose some of the newer emerald treatments, such as Arthur Groom’s Gematrat, to an ultrasonic cleaner. At trade shows, Groom keeps an ultrasonic cleaner at his booth to demonstrate that it’s safe to use with emeralds enhanced this way. But never place an emerald in an ultrasonic cleaner if you are unsure.

Because of potential problems with emerald enhancements, it’s best to adopt a warm-bath-only policy. Wash emerald jewelry with a mild detergent and use a soft brush around the gem. Emeralds are usually set after the jewelry has been fully polished. Then a light touch-up around the prongs is all that’s needed.

Tanzanite

Tanzanite has a hardness of 6 to 7 on the Mohs scale. What really causes problems is its lack of toughness, since tanzanite tends to cleave or fracture very easily.

With tanzanite, the first rule is not to boil. Thermal shock is sure to damage this gem. You also shouldn’t use ultrasonic cleaners and steamers. In addition, be careful when setting it. If you apply too much pressure, it can fracture.

Several years ago, a bench jeweler called me for help. He had set a tanzanite for a retail store and noticed a fracture in the center of the gem. He replaced the tanzanite for the store and went on to fracture this second gem as well. When he called me, I asked him to describe everything he had been doing. It turns out that both gems had survived the setting process, but then he was using an ultrasonic cleaner after polishing. After two damaged tanzanites, this shop will never place another tanzanite in an ultrasonic cleaner.

Treat tanzanite with extreme care. As with emeralds, the setting process should be the last step after the jewelry is completely polished and boiled. Again, the final step is washing with warm soapy water and a soft brush. For the consumer, the advice on care is the same. Your customers should use only the water, detergent, and brush at home. When the jewelry no longer looks like new, then it’s time for professional cleaning.

Opal

There’s a lot of misinformation regarding opal care. Opal consists of spheres of silica surrounded by water. From the moment an opal is mined, it begins a slight drying process. The key to the care of this gem is to prevent it from excessive drying.

Some opals are destined to lose so much water that tiny, web-like cracks will appear in the gem. This is known as crazing. Once an opal crazes, there is nothing more that can be done to restore the original value. Some opals will craze within a few months and some within a few years. Some mine areas, such as the 17-mile mine in Coober Pedy, Australia, have produced opals that are especially prone to crazing. Most opal, however, will hold up with a little care and should not craze during its lifetime. Some have treated opals with epoxy resins. However, no research has been done on the effectiveness of this treatment in concealing crazing or stabilizing the opal.

Wearing an opal is the best way to care for it. It will draw moisture from the body and the air to replenish the water within the gem. Customers who don’t wear their opals regularly should occasionally place the stones in a jar of water overnight (except assembled opal doublets and triplets). Distilled water is recommended to ensure that dissolved minerals from local water supplies don’t get into the opal.

Do not oil the opal. It’s a common myth that oiling is beneficial. Actually, oil prohibits the passage of light, a necessary ingredient for play of color to be viewed. Oiling will also discolor the opal over time.

Customers should not put an opal in a safety-deposit box. The controlled environment and low humidity in a vault can quickly craze it.

If the opal material is prone to crazing, little can be done to prevent it. Frequent soaking in water is only a temporary cure. Eventually, when the opal is left out to dry, the crazing will appear. Each passing year reduces the chances that an opal will craze.

Pearl

Natural, cultured, fresh-water, and Tahitian pearls are very soft, registering only 2 1/2 to 4 on the Mohs scale. Therefore, they need special care. Pearls shouldn’t be left uncovered (other than when they are being worn, of course) because dust in the environment contains quartz particles that are 7 in hardness. They should be stored in a covered box or soft pouch.

If they do get dirty, gently wipe them clean with a soft cloth of lamb’s wool or a chamois. Vigorously and repeatedly wiping dust from pearls can damage the nacre.

When pearls are sent for restringing, they are washed first. Philip Schneider, president of International Cultured Pearls in Chicago, says his company uses Ivory soap and water. The strand is soaked in this mild solution, and then the old string is cut away. He doesn’t recommend that consumers wash pearls at home, however, because the new string should not get wet.

If spaghetti sauce, makeup, hair spray, or perfume accidentally splashes on the pearls, the customer should use a small amount of water on a cloth and immediately wipe them clean. Although pearls are very porous, the residue will remain on the surface for a while before soaking in. This allows time to safely clean the pearls after a night out before returning them to their covered box.

Some women have a high acidity level in their bodies, signaled by their fingers turning black when they wear gold rings. When pearls are in contact with their skin, the acidity will damage the nacre. The best prevention is to avoid wearing the pearls directly against the skin. If there is skin contact, cleaning the pearls after each use is even more crucial. The catch-22, however, is that moisture from the body and the air is beneficial to the life of the pearl. Pearls do have a substantial water content and can dry out over several years. Wearing them will ensure a longer life.

Richard Drucker is president of Gemworld International in Northbrook, Ill., and publisher of The Guide, a pricing periodical he began in 1982. An international gemstone consultant, he has published numerous books and lectures and conducts seminars.

Amber	Avoid heat or pressure. Acids, strong solvents, and chemicals can cause damage. Do not use ultrasonic cleaners.
Andalusite	Liquid inclusions may burst upon heating. Do not boil. Ultrasonic cleaning is safe.
Apatite	Exposure to heat can cause color loss or change. Some pink apatite may fade in light. Sulfuric and hydrochloric acids can cause damage. Do not boil or use ultrasonic cleaning.
Beryl
Aquamarine	Liquid inclusions may burst upon heating. Hydrofluoric acid can cause damage. To be safe, do not boil; use ultrasonic cleaning with caution if inclusions are present.
Emerald	As a general rule, treat with extreme care. Do not boil or use ultrasonic cleaning. Note, however, that ultrasonic cleaning may be safe with some current enhancement methods. Know what you are dealing with or use only warm, soapy water to clean.
Chrysoberyl
Alexandrite and Cat’s Eye	Stable when exposed to heat, light, and chemicals. However, since high value is involved, use caution and avoid boiling and ultrasonic cleaning when possible.
Corundum
Ruby and Sapphire	Generally safe to boil and use ultrasonic cleaning. With stones of high value, some caution may be prudent.
Diamond	Generally safe to boil and use ultrasonic cleaning, unless fracture-filled.
Diopside, Chrome	Highly sensitive to heat. Hydrofluoric acid can cause damage. Do not boil or use ultrasonic cleaning.
Garnet Group
All varieties	Concentrated hydrofluoric acid may cause damage. Abrupt temperature changes likely to cause fractures. Pyrope melts easily under the jeweler’s torch. Generally safe to boil, but avoid thermal shock. Use care with ultrasonic cleaning.
Iolite	Acids can cause damage. Relatively safe to boil and use ultrasonic cleaning; however, be aware of existing cleavages.
Jadeite and Nephrite	Avoid strong solvents, acids, high heat, and strong sunlight. Jadeite is very tough and generally will withstand boiling and ultrasonic cleaning. Be aware that wax-coated jade could be affected.
Lapis Lazuli	Hydrochloric acid can cause damage. Cyanide solution causes reddish-brown discoloration. Keep dyed strands away from heat, solvents, or harsh detergents. Do not boil or use ultrasonic cleaning.
Malachite	Avoid heat and solvents. Acids can cause damage. Do not boil or use ultrasonic cleaning.
Opal	Avoid all solvents and acids. Opals are highly sensitive to heat. Do not boil or use ultrasonic cleaning.
Pearl	Pearls are attacked by all acids. Avoid any type of solvent or acid, including perfume, hair spray, and perspiration. Do not boil or use ultrasonic cleaning.
Peridot	Uneven or sudden heat may result in fracturing or complete breakage. Hydrochloric acid can cause damage; sulfuric acid can easily cause damage. Do not boil and use caution with ultrasonic cleaning.
Quartz Amethyst and Citrine	Strong heat may turn these gems colorless. Abrupt temperature changes may cause fractures. The stones are soluble in hydrofluoric acid and ammonium fluoride and very slightly soluble in alkalis. Boiling is generally safe, but use caution. Also use caution
Spinel
All Varieties	Light gems may fade under intense heat. Boiling is generally safe. Use caution with ultrasonic cleaning.
Spodumene, Kunzite	Very sensitive to heat and strong light, very slowly attacked by concentrated hydrofluoric acid. Do not boil or use ultrasonic cleaning.
Topaz	Avoid thermal shock. Although boiling is possible, it is not recommended, since thermal shock can cause damage. Because of poor toughness, also use caution with ultrasonic cleaning.
Tourmaline
All Varieties	Sudden temperature changes may cause fracturing. Although boiling is possible, it is not recommended, since thermal shock can cause damage. Use caution with ultrasonic cleaning.
Turquoise	Avoid strong solvents. Highly heat-sensitive; dissolves slowly in hydrochloric acid. Specific gravity liquids (used by gemologists in the identification process), perspiration, and cosmetics may discolor surface. Do not boil or use ultrasonic cleaning.
Zircon
All Colors	Gems abrade easily. Heat may alter color; some gems may revert to original color when exposed to light. Avoid boiling, but ultrasonic cleaning is safe.
Zoisite, Tanzanite	Sudden temperature change may cause fracturing. Hydrochloric and hydrofluoric acid can cause damage. Do not boil or use ultrasonic cleaning.