Hi Ellie… I would have thought it depends on what type of covering you use. I made some gelatine gems for my most recent wedding cake (ended up not using them because the colours didn’t match the rest of the decor), which was to be fondant. From the few I tried, as long as your fondant is dry I didn’t think they melted? perhaps it depends on the recipe used. In the end I went for non-edible gems because the only clear ones I could source weren’t brilliant enough for me, they looked too dull and imo were probably about as palatable as plastic ones anyway XD perhaps some others can give you more advice x
