See my pics and photos in the post above this and also
18th century Chalcedony set also here (think this is from the Corning)
https://www.flickr.com/photos/unforth/3276849897/and here another that shows the transparency a little better.
https://www.flickr.com/photos/unforth/3276849673/in/photostream/edited to add -
oh the irony, oh the ignominy
This link states that Chalcedony was opaque glass ....
http://museovetro.visitmuve.it/en/il-museo/layout-and-collections/glass-18th-century/quote
'THE PLEASURE OF IMITATION: CHALCEDONY AND “LATTIMO” IN THE EIGHTEENTH AND NINETEENTH CENTURY Created so they looked like different materials, various kinds of ‘imitation’ glass were very appreciated in the eighteenth century. Examples include opaline glass, which looked like opal; opaque white glass, called “lattimo” (from the word for milk “latte”), which looked like porcelain and chalcedony, a variegated opaque glass with multicoloured veining, which looked like semi-precious stones such as banded agate, onyx, malachite and lapis lazuli. Known already in the Roman age, chalcedony glass appeared in Murano during the Renaissance; it was made by mixing the remains of white, coloured or opal glass and crystal and adding different mixtures of substances once fused (such as copper, silver, cobalt, etc.) which resulted in its multicoloured veining. At times, from the seventeenth century on, aventurine fragments were also added, resulting in further patches or streaks, for example in the two-handled eighteenth-century cup on display here. The “secret” of chalcedony was lost at the end of the century and it was not until the middle of the nineteenth century that it was revived; this was thanks to Lorenzo Radi who, in 1856, developed the same sixteenth-century composition, creating objects with simple, linear forms of the greatest effect owing to their vast chromatic range of the veining.'http://museovetro.visitmuve.it/en/il-museo/layout-and-collections/glass-18th-century/... But I'm telling you absolutely, that the photos I have uploaded are transparent glass. The only reason they appear opaque is because the light reflects off the glass in the photos. Close up, in person, you can see through them.
According to that link
' ... this was thanks to Lorenzo Radi who, in 1856, developed
the same sixteenth-century composition, creating objects with simple, linear forms of the greatest effect owing to their vast chromatic range of the veining.'
I'm busily trying to hunt down a definite Lorenzo Radi piece because the two pieces I have seen id'd as his (look thick and very opaque) don't appear to be the same composition or effect as those 18th century pieces I have linked to.
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