Retro jewelry is a style that was popular in the late 1930's and 1940's and that peaked during WWII. It is known for its bold scale, romantic scrolling curves, and naturalistic imagery, moving away from the more hard-edged geometry of the Art Deco style that preceded it.
The most notable change is that Retro jewelry is typically made of yellow and rose gold, often utilizing both shades of gold in a piece of jewelry, a major change from the platinum and white gold jewelry that was dominant for the previous four decades. The switch to the use of gold was the result of platinum being declared a "strategic metal" in WWII, with very limited availability. The war also affected the availability of gemstones, especially diamonds and natural rubies and sapphires; as a result, Retro jewelry is notable for incorporating large semiprecious stones such as citrine, amethyst, and moonstone and using synthetic rubies and sapphires and small diamonds as accents.