Information about the used materials
Pure silver (999.9%) is a white-colored metal that is too soft for most purposes of jewelry making. Therefore, a small amount of copper is usually added to make the silver more durable. Sterling silver contains 92.5 % silver and 7.5 % copper. The copper slowly oxidizes when exposed to air which accounts for some of the discoloration that naturally occurs in some silver ornaments. Also, silver can tarnish (turn black) when exposed to air because of a chemical reaction with sulphur. This process is unavoidable, and the rate of tarnishing depends on pollution and moisture content of the air and can be accelerated by exposure to oils on your skin or from your fingers, ammonia, and chlorinated water to name a few. Silver jewelry can be polished to look fresh and shiny again using polish cloth or cleaning liquids that can be obtained from jewelry stores.
Pearls come in a variety of shape, color, and size, and can be cultivated in freshwater or in salt water. The pearls I use are all freshwater pearls and mostly originate from freshwater ponds in the Philippines and China. Cultivated pearls are created by inserting a small piece of shell in the mantle of a mollusk, who then deposits a layer of nacre (a natural lustrous substance, also called 'mother-of-pearl') around the irritant. Each mollusk species produces a slightly different type and color of nacre, which is also influenced by the temperature and quality of the water. Freshwater molluscs usually produce pearls that have a characteristic uneven surface. Pearl farmers produce pearls of different size and shape by using different sizes and shapes of the shell insertions. Popular shapes include round and half-round spheres, discs, coins, teardrops, sticks, squares, and diamonds. Nacre gives pearls their natural color, most often white, pink, silver, gray, yellow, brown, or gold. The "body" color is the predominant basic color of the pearl. This is often complemented by "overtones", one or more colors overlying the body color. The "orient" or "pearl iridescence" is a play of lustrous or rainbow colors of usually violet, blue, red, green, yellow or orange. The "lustre" of a pearl is the surface brilliance which depends on the quality and quantity of the reflected light. Pearl farmers or traders can dye pearls either during the cultivation process or after.
Glass is an amorphous (non-crystaline) solid material, made of a combination of silica (usually aorund 75%), chalk and soda, and several minor additives. Different colors are obtained by the addition of metaloxides of copper, iron, cobalt, gold, or others. For bead making, I use mostly Moretti soft glass rods from the Effetre factory in Murano, Italy. The rods are typically 35 cm long with a diameter of 2 to 6 mm. I heat the rods with a torch up to temperatures of 1800 to 2100 degrees Celsius till they start melting and I can produce the shapes and color combinations I want.
A gemstone is a piece of mineral, which, in cut and polished form, is used to make jewelry or other adornments. However, certain rocks (such as lapis lazuli and turquoise) are not minerals, but are still used for jewelry, and are therefore considered to be gemstones as well. The traditional classification in the West, which goes back to the ancient Greeks, makes a distinction between precious and semi-precious stones, which is not a scientific distinction but reflects the rarity and contemporary appreciation and value of the stones. In modern usage, the precious stones are diamond, ruby, saphire, aquamarine, and emerald, with all other gemstones being semi-precious [adapted from Wikipedia, July 2011]. Below, I give some information about the gemstones I use most:
- Agate: a cryptocrystaline quart (SiO2), or chalcedony, whose crystals are so minute that they can't be seen with the naked eye. Agate is banded or has branching inclusions, often in shades of red, orange, roze, pink, blue, or white. It has a waxy luster, extremely small crystals, and a specific hardness of 7.
- Lapis lazuli (also called Lazurite or Hauynite): a sodium-calcium aluminium silicate with sulphate-sulphur, usually occurring in amorphous form of dark-blue and white colors, sometimes with interspersed veins of gold-colored pyrite. The specific hardness is 5-5.5.
- Onyx: an agate with straight, even banding, usually white and black or shades of green.
- Sodalite: a sodium aluminium silicate with chlorine of varying chemical composition. Occurs usually in amorphous masses, though crystals up to 100 mm have been found. The color varies from colorless, to blue, white, yellow, and pink, though, like like lapis lazuli, the color used in gemstones is usually dark blue with white inclusions. The specific hardness is 5-5.5.
- Turqouise: a fine-grained, hydrous basic copper aluminium phosphate, usually occurring as dense masses or crusts with a delicate brown or white colored veining. The base color is pale blue, blue-green, or green. The color mostly derives from copper sulfides. The specific hardness is 5-6.