1890-1900: Classic solitaire diamond ring: Round old European-cut diamond set into a six prong mounting, 14k yellow gold.
1900-1920s: Lacy white-on-white look, in the style of jewelry of the Edwardian period.
1920-1930s: Art Deco–influenced rings: Round early modern brilliant-cut diamond set into a platinum mounting, highlighted by round diamonds in a pierced openwork mounting.
1930-1940s: The introduction of white gold in the late 1920s; "filigree" mounting, which heralds back to the Edwardian period, comes in trend.
1940s: Yellow and rose gold used more.
1945: "War Bride Ring," the ring that every serviceman gave their fiancée due to the rationing of precious metals during the war years.
1950-1960s: White gold and platinum becomes the preferred metal in postwar period. Addition of round side stones set into the shoulders of the ring.
1960-1970s: Fancy-shaped diamonds—emerald-cut, pear, marquise, and heart shaped—become in. Platinum remains metal of choice.
1970-1980s: "Gold" set with round or fancy shaped diamonds with channel set mountings, accompanying wedding bands.
1980-1990s: Solitaire diamond with baguettes on each side.
1990-2000s: "Radiant-cut" becomes the preferred fancy-shaped diamond, typically set with triangular side stones.
2000-2010s: "Princess-cut" becomes the preferred fancy-shaped diamond.
2010-2015: "Halo" mounting becomes the preferred engagement mounting; increased demand for fancy-colored diamonds.