Methods and risks
Maintaining a clean diamond can sometimes be difficult, as jewellery settings can obstruct cleaning efforts, and oils, grease, and other hydrophobic materials adhere well to a diamond's surface. Some jewelers provide their customers with sudsy ammonia cleaning kits. Many jewelers use steam cleaners. Some other jewelers sell small ultrasonic cleaners. Home-based cleaning methods include immersing the diamond in ammonia-based or ethyl alcohol-based solutions, or even a solution of mild grease dissolving detergent and warm water. Silver jewelery can be cleaned using aluminum foil, baking soda, and hot water. However, this practice is not recommended by most jewelers.
Certain types of cleaning can damage some jewellery. For example, some class rings are coated with a dark pigment to reduce their shininess. Some gemstones, such as white topaz, have an overlay to produce certain colors. Ultrasonic cleaning can remove this coating, if it is not a quality piece. Ultrasonic cleaning is also contraindicated for opals, pearls and amber, and any other gemstone that is porous. Gemstones that are glued in (a common practice with semiprecious stones in non-precious methods, and in class rings) should not be placed into an ultrasonic cleaner. An ultrasonic cleaner can cause stones that are loose in their settings to come out. Jewellery should always be examined for overlays and loose stones prior to cleaning with an ultrasonic cleaner or a steam cleaner.
There are a number of things you can do to prevent build up of dirt and prevent jewellery becoming tarnished. Namely; Store jewellery carefully in its original packaging or a jewellery box. Clean jewellery using warm water, mild soap and a soft bristle toothbrush. Use a non abrasive silver cloth or soft lint free cloth to polish jewellery and remove tarnishing. Don't expose jewellery to harsh chemicals or perfumes as this could cause damage and discoloration. Don't wear jewellery when doing anything heavy duty and avoid unnecessary knocks and scratches. Try to avoid spraying your jewellery with beauty products such as hair spray, cosmetics or perfume as this can tarnish or discolour the jewellery. Always put your jewellery on last. Clean your jewellery on a regular basis. Bangles, earrings (particularly those manufactured from hollow tubing) and chains should be worn with care in order to avoid surface damage, and should be removed before going to bed. Check for signs of wear and tear regularly, especially on catches and joints. Stone settings can become loose over time, especially if they have been hit against a hard surface or snagged on clothing.
Beauty of gems
Although it is not one of the 4 C's, cleanliness affects a diamond's beauty as much as any of the 4 C's (cut, carat, color, clarity).
A clean diamond is more brilliant and fiery than the same diamond when it is "dirty". Dirt or grease on the top of a diamond reduces its lustre. Water, dirt, or grease on the bottom of a diamond interferes with the diamond's brilliance and fire. Even a thin film absorbs some light that could have been reflected to the person looking at the diamond.
Colored dye or smudges can affect the perceived color of a gem. Historically, some jewelers' diamonds were misgraded due to smudges on the girdle, or dye on the culet. Current practice is to thoroughly clean a gem before grading its color as well as clarity.
Cleanliness does not affect the jewellery's market value, as jewelers routinely clean jewellery before offering it for sale. However, cleanliness might reflect the jewellery's sentimental value.