In general, it is inadvisable to use a brush for cleaning jewelry, as it tends to loosen the stones. Eventually—not while being cleaned, but during an otherwise pleasant evening—a stone may fall from the setting. Ammonia, soap, and other cleaning agents are likely to leave a film. This may be imperceptible; a woman may think she has “cleaned it all off”; and yet it may greatly lessen the brilliance of the stone. Soaking in boiling water—with or without chemicals—is dangerous. Some alloys as well as some stones cannot stand such treatment. Likewise sudden heat, or sudden cooling, may seriously damage certain stones; some may even crack, or break. Most delicate are the emerald, the peridot, the aquamarine, and the turquoise. The turquoise especially should not come into contact with fatty or oily substances. It is porous, and such substances are likely to change its color, or to make it dull. In every case, when she is tempted to apply home cleaning to her jewels, a woman should remember that the jeweler is equipped with steam blowers and other modern devices, each for its particular type of stone, and he is glad to be called upon to give his expert knowledge and gentle care. _Pearls_ Perhaps most care is required in the handling of the pearl. Boiling, for example, is almost sure to loosen any pearls in a jewel. All chemicals are to be avoided. For casual cleaning, a pearl necklace may be wiped with a clean and slightly damp cloth. It should not be pulled; the best way is to roll it on a towel. If the necklace becomes too wet, the string may become loosened. A pearl necklace, indeed, should be regularly restrung; there is little sense in waiting until it breaks. When the knots near the clasp of the necklace have become grey, restringing time has come. One must be careful not to put perfume, or any liquid containing alcohol, on, or close to, pearls. They may lose their lustre, or even start to peel. At the hairdresser’s, pearls should of course be removed before any treatment. The heat of the dryer, for example, may loosen the pearls in their settings. _Reminders_ Some of the things in this chapter I have already said; this is a time for reminders. And one important reminder is that, even if the front pearls are strung without knots—and they will be more lustrous if thus close together—a few pearls on each side of the clasp should always be knotted. That is the danger spot for breaks. Another helpful reminder is that elaborate jewels may be made with removable or convertible parts. I have discussed in detail how a very formal jewel, likely to be worn on rare occasions, may be so fashioned that, in various smaller units, it can be enjoyed more freely and frequently.