It is interesting to note, that with micro mosaic images of St Peters Square you can easily tell which half of the 19th
century these were created, as there are two distinct time frames that are shown. Between 1852 - 1854, four large gas lamps were added to the square, close around the central obelisk, and these were documented in micro mosaics. You can see them in the example of the box and paperweight. However, they are a noticeable absence in the central plaque of the slate tray which means this tray is an earlier example.
The other anecdote of interest relates to the brooch with the “goldstone” border. Goldstone which is not a gemstone at all, but a type of glittery glass is believed to have been invented by the monks within the Vatican and its secret tightly held. By referring to it as “goldstone” it came to be rumoured that there was, in fact, a secret mine located in the Vatican itself of this rare gemstone. Interestingly, many people today still believe goldstone is a mineral.
Like all things after the industrial revolution, as time was equated in direct proportion with cost then micro mosaic became less micro and more just mosaic. As a result of this most of the examples produced in the 20th
century are generally quite coarse and crude and lack the subtle shadings of earlier examples. This also limited the subject matter more to floral designs which could be created with a single tessera representing a petal, rather than pictures which might require more details and shading to convey the image.
As a result, the technique and the complexity of these earlier pieces has driven people to avidly collect them and so these souvenirs of an Italian Grand Tour, have become very sought after miniature masterpieces.
For a quick look at how micro mosaic in jewellery is made:https://www.youtube.com/watch?v=nNdwvR17aNo