I have these jewel molds that I have never used, and some isomalt sticks that I bought this summer so I thought about actually using them on a cake this weekend. The cake will be buttercream.

I'm wondering if the sugar jewels are something that needs to be put on the day of, or if it is okay to put them on the day before. Since I haven't worked with the isomalt and a cake before I didn't know if the moisture in the icing would cause the jewels to start to melt.

Anyone have any problems with them and buttercream and melting issues?

I've never used jewels before, but have ordered some online. From what I've read, they are very sensitive to moisture and humidity, so resulting in the jewel to go 'foggy', and should be placed on cake as late as possible. I'll be using them on fondant, not quite sure what they'd be like on buttercream.