In most fields, there is a defining period or two that can be referred to as the ‘Golden Age’. In Hollywood, an extended period starting from the 1920s to the 1960s is accredited as that. In the jewelry segment, that would be the Art Deco period.
The Edwardian period saw engagement rings turn into a widely accepted custom in the society. The industrial revolution brought more prosperity and saw the emergence of a burgeoning middle class in America and much of Europe, so people could afford fine jewelry more than ever before. The engagement rings of that period often featured diamonds in ornate and lacy platinum band designs.