Although jewellery is proven to be one of the oldest trades, a product of man's desire for self adornment, the historical evidence of rings seems to start in ancient Babylonia in approx 2500BC but is disjointed (please excuse the pun) due to the fact that rings are not the most practical items to wear in societies that favoured hard labour and war. Understandably there is a plethora of ancient collars, amulets, cloak pins and brooches. Rings were a symbol of power for a very long time, traditionally to denote status, rank or family. It is therefore no surprise that the signet ring style has the longest near continuous history. However, in late Dynastic Egyptian society there is plenty of evidence of finger rings, some of which are early examples of marital gestures. A complete gold ring might reflect the cyclical and eternal nature of their Sun God devotion. In one continuous gold band (shown below right), there are interlocking images of the deity Bes. Bes, was an Ancient Egyptian Deity worshipped as a protector of households, and in particular, of mothers, children and childbirth. Possibly the first evidence of an eternity ring?
There is further evidence of marital or eternity bands being fashionable in Roman times, particularly in the early Christian era around 500AD. Rings were decorated with engraved portraits of couples pictured between crucifixes. Engravings have always been enormously helpful to denote ring use which include devotional, political, magical and romantic themes. From Mediaeval times, rings often just followed the fashion of the times so we may assume that they were presented for all types of occasion whether as investiture, reward or personal. By the seventeenth century, more commercial jewellery is in evidence, with stones and styles to a standard that could easily be unset and remoulded into the mode of the time. The 'Cheapside Hoard', exhibited at the Museum of London, is the perfect example of this.
By the early twentieth century, due to a combination of the Suffragette movement, the Great War and the carefree attitude of the Roaring Twenties, the fashion had changed. Women were working, relatively wealthy and expressed their new found liberties in fashions including jewellery. Eternity style rings, as we know them today (a continuous band of stones), would be stacked on fingers. The linear nature of the bands perfectly reflecting the Art Deco culture of design. Platinum was dominant and diamonds were the gemstone of choice although they were often complemented by bands containing rubies, sapphires and emeralds as bold primal contrasts.
Due to the hardships and rationing of World War Two, jewellery production and innovation virtually stopped until the further revolutions of the Fifties and beyond. The Digital Age of the Twenty First century has provided pioneering designers with new ways to create eternity rings using 3D printing technologies that have made previously impossible designs possible. Have a look at the GUY&MAX wireframes in their Birdcage Collection eternity rings. But I would say that.