Hi Stephane, welcome to the Board.
I am sure Wuff will give further comment, but while I am here, I thought I would offer this ...
The French word "sulfure" is believed to be the origin of the English "sulphide" (and also "sulfide" in modern American English). The term was applied to medallions, often depicting famous people, made with moulds using a form of ceramic ("clay" or "plaster"). Usually these were left in the original white or off-white but were sometimes coloured. They were used in a variety of ways but often as decoration to the sides of such as Baccarat decanters and tumblers. They were also used as internal decoration in clear glass paperweights.
In your Murano apple paperweight, the worm is formed from a length of coloured glass which has striping in a contrasting colour. The rod of glass is heated and shaped with tweezers before being set into the clear glass and then covered with more clear. It is not a "sulphide" as it is a piece of hand-shaped glass, rather than being a moulded piece of "clay / plaster" ceramic.
But, yes, in modern times some people do seem to use "sulphide" when referring to what is actually "lampwork" (or "torchwork", for those whose prefer that term).