Art Deco received its moniker from the Exposition International des Arts Décoratifs et Industriels Modernes, held in Paris in 1925, which was largely dedicated to the jewelry arts. Emphasis was placed on the association of art and modern industry. Inspiration for this style was as far reaching as Oriental, African and South American Art and as varied as Cubism and Fauvism, both popular movements at the time. The term "Cubism" was often used to describe jewelry of this era because of the angles, geometric lines and figurative representations used in its execution. A desire to eliminate the flowing lines of Art Nouveau and distill designs to their rudimentary geometric essence, thus eliminating seemingly unnecessary ornament, resulted in the cleaner and more rigid lines employed in Art Deco jewelry. A look forward toward modernism and the machine age also featured prominently at this juncture in jewelry history.
During the Art Deco era, advancements in cutting techniques, including the advent of the modern round brilliant cut style, allowed for diamonds to become more dazzling and scintillating than ever before. Meanwhile, prosperity was permitting more people to afford diamond jewelry and engagement rings. New casting techniques further increased accessibility, as jewelers discovered more efficient ways to produce the most intricately detailed of settings.
In the early 1900s, diamond cutters began to experiment with new techniques. A breakthrough came in 1919 with the introduction of the round brilliant cut. Due to its ability to maximize fire and brilliance, the round brilliant cut has become the standard and most popular way to cut diamonds. Like the old European cut, a round brilliant cut diamond has a circular girdle and 58 facets. However, the round brilliant cut lacks a culet. The round brilliant cut became prevalent during the Art Deco and Retro periods.
The most popular form of sapphire is blue sapphire, which is known for its medium to deep blue colour and strong saturation. Fancy sapphires of various colours are also available. In the United States, blue sapphire tends to be the most popular and most affordable of the three major precious gemstones (emerald, ruby, and sapphire).
Because of the softness of pure (24k), it is usually alloyed with base metals for use in jewelry, altering its hardness and ductility, melting point, color and other properties. Alloys with lower carat rating, typically 22k, 18k, 14k or 9k, contain higher percentages of copper or other base metals or silver or palladium in the alloy. Copper is the most commonly used base metal, yielding a redder color.