There are two similar weights to this in Paperweights by Sybil Jargsdorf.
Both by Ferro and Lazzarini as Sophie has said.
One on page 57 which is a lampworked flower bouquet in a mushroom type shape and on a very similar aventurine ground to your weight.
The other is on page 58 which also has a similar ground I think and has the aventurine shapes. In this weight these look like balls of aventurine bobbles in ball shaped clusters floating above the ground.
It's difficult to tell from the pics whether they are on a black 'base' ground underneath the aventurine but I think it's possible they are. I have two of their weights, one of which is very similar to one described in the book and where the book doesn't denote that it is on a dark ground, but it is (in this case dark blue, in the case of my other one, it is black).
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