Hello Simon,
you have replied in the lily-of-the-valley case, and via the Apsley Pellatt thread I have found, that the fascinating Venezian plaque is your's!
I always wanted to know more about this piece, and bought a round aventurine weight in Germany a couple of years ago; as far as I can see, it has a related cane type (three times) enclosed. It is not signed, but it may be a piece that was sold along a Trade Exhibition in the 1840/1850ies; (Bigaglia - in 1845 in Vienna, first time, then he was attending many Fairs, even at the 1851 WTF in GB...and hopefully sold a lot of what he brought with him!) The type of square paperweights surely has a very long tradition, more of them were made in marble or micro mosaic, and in Russia as square flat bouquets- the most expensive weight one could find! The micro mosaics were an Italian souvenir top-seller and possibly a millefiori predecessor...
The blue-red-white cane was surely inspired by a famous and traditional bead design called chevron bead, which can be found a long time back in history...
kind regards, Erhard