Most modern commercial jewellery continues traditional forms and styles, but designers have widened the concept of wearable art. The advent of new materials, such as plastics, Precious Metal Clay (PMC), and colouring techniques, has led to increased variety in styles. Other advances, such as the development of improved pearl harvesting and the development of improved quality artificial gemstones, has placed jewellery within the economic grasp of a much larger segment of the population.
Onyx is the name for the black and white banded variety of chalcedony. It has been used since antiquity when it was highly prized as a cameo stone. The layered color structure allows the engraver to cut the subject in one color while creating a background of another. The term onyx is often encountered describing pure black material although this is technically incorrect.
Marcasite is an iron sulfide mineral with an orthorhombic crystal structure. It is very brittle and unsuitable for jewelry. What we call "marcasite" in jewelry is actually Pyrite – "fools gold" – that has been faceted to imitate diamonds. Popular from around 1700 onward, marcasite is usually found mounted in silver. Because of its golden yellow color and metallic luster, Marcasite has remained popular in higher quality fashion jewelry. In antique jewelry, marcasite can be distinguished from cut steel faux gems because marcasites are usually bead or prong-set as a gemstone would be and cut steel is riveted.
Silver is a white metallic element, harder than gold, softer than copper and second only to gold in malleability and ductility. Represented on the Periodic Table of the Elements by the symbol Ag, silver is an excellent conductor of heat and electricity. Silver is considered one of the noble metals because of it is excellent resistance to oxidation. Historically, silver has played a prominent role in the production of jewelry an objets d'art and is usually alloyed with another metal to harden it enough to maintain the desired shape and details imparted to it.